FORMAT: 1A

# OpenProject API v3

# Group General

This is the current **DRAFT** of the specification for OpenProject APIv3.

Please note that everything in this document might be **subject to change** in a future version of OpenProject. We intend to keep this specification
as accurate as possible, however as long as the APIv3 is not in a stable state it is possible that there are intermediary differences between
this specification and the real implementation. While we try to only specify what we want to keep, it might also happen that parts of this
specification will be replaced **incompatibly** until the APIv3 is considered *stable*.

# Hypermedia
TODO: Description & Resources

# Formats
TODO: Description and why only JSON

# HAL+JSON

HAL is a simple format that gives a consistent and easy way to hyperlink between resources in your API.
Read more: http://stateless.co/hal_specification.html

**OpenProject API implementation of HAL+JSON format** enriches JSON and introduces a few meta properties:

    - `_type` - specifies the type of the resource (e.g.: WorkPackage, Project)
    - `_links` - contains all links available for the resource
    - `_embedded` - contains all embedded objects

HAL does not guarantee that embedded resources are embedded in their full representation, they might as well be
partially represented (e.g. some properties can be left out).
However in this API you have the guarantee that whenever a resource is **embedded**, it is embedded in its **full representation**.

# API response structure

All API responses contain a single HAL+JSON object, even collections of objects are technically represented by
a single HAL+JSON object that itself contains its members. More details on collections can be found
in the [Collections Section](#collections).

# Authentication

For now the API only supports two authentication schemes: session based authentication and basic auth.
Depending on the settings of the OpenProject instance many resources can be accessed without being authenticated.
In case the instance requires authentication on all requests the client will receive an **HTTP 401** status code
in response to any request.
Otherwise unauthenticated clients have all the permissions of the anonymous user.

## Session-based Authentication

This means you have to login to OpenProject via the Web-Interface to be authenticated in the API.
This method is well-suited for clients acting within the browser, like the Angular-Client built into OpenProject.

## API Key through Basic Auth

Users can authenticate towards the API v3 using basic auth with 'apikey' as the user name and their API key as the password. Users can find their API key on their account page.

Example:

```bash
API_KEY=2519132cdf62dcf5a66fd96394672079f9e9cad1
curl -u apikey:$API_KEY https://community.openproject.com/api/v3/users/42
```

### Why not username and password?

The simplest way to do basic auth would be to use a user's username and password naturally.
However, OpenProject already has supported API keys in the past for the API v2, though not through basic auth.

Using **username and password** directly would have some advantages:

* It is intuitive for the user who then just has to provide those just as they would when logging into OpenProject.
* No extra logic for token managment necessary.

On the other hand using **API keys** has some advantages too, which is why we went for that:

* If compromised while saved on an insecure client the user only has to regenerate the API key instead of changing their password, too.
* They are naturally long and random which makes them invulnerable to dictionary attacks and harder to crack in general.

Most importantly users may not actually have a password to begin with. Specifically when they have registered
through an OpenID Connect provider.

## Future Work

For the future we plan to add authentication modes based on OAuth2 and OpenID Connect.

# Allowed HTTP methods

- `GET` - Get a single resource or collection of resources
- `POST` - Create a new resource or perform
- `PATCH` - Update a resource
- `DELETE` - Delete a resource

# Compression

Responses are compressed if requested by the client. Currently [gzip](http://www.gzip.org/) and [deflate](https://tools.ietf.org/html/rfc1951)
are supported. The client signals the desired compression by setting the [`Accept-Encoding` header](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.3).
If no `Accept-Encoding` header is send, `Accept-Encoding: identity` is assumed which will result in the API responding uncompressed.

# Group Basic Objects

# Links

Links to other resources in the API are represented uniformly by so called link objects.

## Local Properties

| Property  | Description                                                              | Type    | Required | Nullable | Default     |
|:---------:| ------------------------------------------------------------------------ | ------- |:--------:|:--------:| ----------- |
| href      | URL to the referenced resource (might be relative)                       | String  |    ✓     |    ✓     |             |
| title     | Representative label for the resource                                    | String  |          |          |             |
| templated | If true the `href` contains parts that need to be replaced by the client | Boolean |          |          | false       |
| method    | The HTTP verb to use when requesting the resource                        | String  |          |          | GET         |
| payload   | The payload to send in the request to achieve the desired result         | String  |          |          | unspecified |

All link objects *must* contain the `href` property, though it might be `null`. Thus the following is a valid
link object:

    {
        "href": null
    }

whereas `{ }` is not a valid link object. The meaning of `"href": null` is that **no** resource is referenced.
For example a work package without an assignee will still have an assignee link, but its `href` will be `null`.

If a `title` is present, the client can display the title to the user when referring to the resource.

Templated links are links that contain client replaceable parts. Replaceable parts are enclosed in braces. For example
the link `api/v3/example/{id}` is not complete in itself, but the client needs to replace the string `{id}` itself.
As of now the API does not indicate the valid replacement values.

The `method` indicates which HTTP verb the client *must* use when following the link for the intended purpose.

If a `payload` is specified, it needs to be sent as the body of the request to achieve the desired result (e.g. perform the
action represented by the link). If no `payload` is specified, there is either no payload to send or a valid payload is not specified
by the link object. A payload might also be templated slightly. If the `templated` property is true, a payload might contain replaceable parts
in its strings (e.g. `{ "href": "/api/v3/examples/{example_id}" }`).

Note: When writing links (e.g. during a `PATCH` operation) only changes to `href` are accepted.
Changes to all other properties will be **silently ignored**.

# Errors

In case of an error, the API will respond with an apropriate HTTP status code.
For responses with an HTTP status of `4xx` and `5xx` the body will always contain a single error object.
Error objects shall give the client additional details about the cause of an errorneous response.

## General errors

* Error objects have their `_type` set to `Error`
* The `errorIdentifier` serves as a unique (and machine readable) identifier for a specific error cause
    * There *may* be multiple possible error identifiers per HTTP status code
    * There *may* be multiple possible HTTP status codes per error identifier
    * The "List of Error Identifiers" defines the possible mappings between HTTP status and error identifier
* The `message` contains a human readable concise message describing the error
    * It *optionally* includes specific information, for example which permission would have been needed to perform an action
    * It is localized depending on the users preferences
    * It *must not* include HTML or other kind of markup
    * Error messages form complete sentences including punctuation

### Example

    {
        "_type": "Error",
        "errorIdentifier": "urn:openproject-org:api:v3:errors:InternalServerError",
        "message": "An internal server error occured. This is not your fault."
    }

## Embedded error information

Errors might optionally contain embedded objects that contain further information.

### Error details

Under the embedded key `details` there might be an object describing the error more verbosely. For example if the
error affects a specific field, this field could be defined there.

#### Example

    {
        "_type": "Error",
        "errorIdentifier": "urn:openproject-org:api:v3:examples:ExampleError",
        "message": "This is an example error.",
        "_embedded": {
            "details": {
                "_type": "ExampleErrorDetailInformation",
                "errorneousField": "subject"
            }
        }
    }

### Multiple error objects

To ease implementation of basic clients it is guaranteed that the response body always only contains a single error object.
However it is allowed that an error object *embeds* other error objects under the key `errors`, thereby aggregating them.

The `errorIdentifier` of such an object is always `urn:openproject-org:api:v3:errors:MultipleErrors`. The message can either describe one of the
embedded errors or simply state that multiple errors occured.

#### Example

    {
        "_type": "Error",
        "errorIdentifier": "urn:openproject-org:api:v3:errors:MultipleErrors",
        "message": "Multiple fields violated their constraints.",
        "_embedded": {
            "errors": [
                {
                    "_type": "Error",
                    "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                    "...": "..."
                },
                {
                    "_type": "Error",
                    "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                    "...": "..."
                }
            ]
        }
    }

## List of Error Identifiers

* `urn:openproject-org:api:v3:errors:InvalidQuery` (**HTTP 400**) - The query contained a value that did not match the servers expectation
* `urn:openproject-org:api:v3:errors:InvalidRequestBody` (**HTTP 400**) - The format of the request body did not match the servers expectation
* `urn:openproject-org:api:v3:errors:InvalidRenderContext` (**HTTP 400**) - The client specified a rendering context that does not exist
* `urn:openproject-org:api:v3:errors:InvalidUserStatusTransition` (**HTTP 400**) - The client used an invalid transition in the attempt to change the status of a user account.
* `urn:openproject-org:api:v3:errors:Unauthenticated` (**HTTP 401**) - The client has to authenticate to access the requested resource.
* `urn:openproject-org:api:v3:errors:MissingPermission` (**HTTP 403**) - The client does not have the needed permissions to perform the requested action
* `urn:openproject-org:api:v3:errors:NotFound` (**HTTP 404**) - Default for HTTP 404 when no further information is available
* `urn:openproject-org:api:v3:errors:UpdateConflict` (**HTTP 409**) - The resource changed between GET-ing it and performing an update on it
* `urn:openproject-org:api:v3:errors:TypeNotSupported` (**HTTP 415**) - The request contained data in an unsupported media type (Content-Type)
* `urn:openproject-org:api:v3:errors:PropertyIsReadOnly` (**HTTP 422**) - The client tried to set or change a property that is not writable
* `urn:openproject-org:api:v3:errors:PropertyConstraintViolation` (**HTTP 422**) - The client tried to set a property to an invalid value
* `urn:openproject-org:api:v3:errors:PropertyValueNotAvailableAnymore` (**HTTP 422**) - An unchanged property needs to be changed, because other changes to the resource make it unavailable
* `urn:openproject-org:api:v3:errors:ResourceTypeMismatch` (**HTTP 422**) - A link to a resource of a specific type was expected, but the link to another type of resource was provided
* `urn:openproject-org:api:v3:errors:PropertyFormatError` (**HTTP 422**) - A property value was provided in a format that the server does not understand or accept
* `urn:openproject-org:api:v3:errors:InternalServerError` (**HTTP 500**) - Default for HTTP 500 when no further information is available
* `urn:openproject-org:api:v3:errors:MultipleErrors` - Multiple errors occured. See the embedded `errors` array for more details.

# Formattable Text

OpenProject supports text formatting in Textile. Other text formats *may* be introduced in the future.
Properties that contain formattable text have a special representation in this API. In this specification their
type is indicated as `Formattable`. Their representation contains the following properties:

| Property | Description                                        | Type   | Example                            | Supported operations |
|:--------:| -------------------------------------------------- | ------ | ---------------------------------- | -------------------- |
| format   | Indicates the formatting language of the raw text  | String | textile                            | READ                 |
| raw      | The raw text, as entered by the user               | String | `I *am* formatted!`                | READ / WRITE         |
| html     | The text converted to HTML according to the format | String | `I <strong>am</strong> formatted!` | READ                 |

`format` can as of today have one of the following values:

* `plain` - only basic formatting, e.g. inserting paragraphs and line breaks into HTML
* `textile` - formatting using Textile
* `custom` - There is no apparent formatting rule that transforms the raw version to HTML (only used for read only properties)

More formats might be added in the future.

Note that `raw` is the only property supporting the **write** operation. A property of type *Formattable* that
is marked as **read and write**, will only accept changes to the `raw` property. Changes to `format` and `html` will be **silently ignored**.
It is thus sufficient to solely provide the `raw` property for changes.

If the *Formattable* is marked as **read only**, the `raw` attribute also becomes **read only**.

#### Example

    {
        "format": "textile",
        "raw": "I *am* formatted!",
        "html": "I <strong>am</strong> formatted!"
    }

# Dates, Times and Durations

Representation of time related values in this API is done according to [ISO 8601](http://en.wikipedia.org/wiki/ISO_8601).
In this specification the following terms will be used as type specifiers (e.g. in tables):

* `Date` - refers to an ISO 8601 date, e.g. "2014-05-21"
* `DateTime` - refers to an ISO 8601 combined date and time, e.g. "2014-05-21T13:37:00Z"
* `Duration` - refers to an ISO 8601 duration, e.g. "P1DT18H"

# Colors

Colors are represented in RGB using hexadecimal notation as specified in [CSS Color Module Level 3](http://www.w3.org/TR/css3-color/).
That is a `#` followed by either three or six hexadecimal digits.

#### Examples

    red:   #ff0000 or #f00
    green: #00ff00 or #0f0
    black: #000000 or #000
    white: #ffffff or #fff

# Digests

Digests (or Hashes) are one way functions that map data of arbitrary size to data of a fixed size.
In OpenProject they are for example used to calculate checksums for (attachment) files.
The checksum calculated depends on the hashed data and the algorithm used as hash function.

Therefore all digests are represented in the following form:

| Property  | Description                                        | Type   | Example                            |
|:---------:| -------------------------------------------------- | ------ | ---------------------------------- |
| algorithm | The algorithm used to compute the digest           | String | md5                                |
| hash      | The calculated digest in hexadecimal notation      | String | 64c26a8403cd796ea4cf913cda2ee4a9   |

#### Example

    {
        "algorithm": "md5",
        "hash": "64c26a8403cd796ea4cf913cda2ee4a9"
    }

# Group Collections

Whenever a client calls a resource that can return more than one element, it will receive a collection of elements.
However as collections can become quite large, the API will **not** simply return a JSON array, but a special collection
object that will contain the actual elements in its embedded property `elements`.

Collections *may* be paginated, this means that a single response from the server will not contain all elements of the collection,
but only a subset. In this case the client can issue further requests to retrieve the remaining elements.
There are two ways to access the result pages of a paginated collection:

* offset based pagination
* cursor based pagination

The available ways of pagination depend on the collection queried. Some collections feature no pagination at all, meaning they
will always return all elements. Others might only offer one of the two pagination methods or both of them.
An explanation of [offset](#collections-offset-based-pagination) and [cursor](#collections-cursor-based-pagination) based
pagination can be found below the links table.

A collection also carries meta information like the total count of elements in the collection or - in case of a paginated collection -
the amount of elements returned in this response and action links to retrieve the remaining elements.

## Local Properties

| Property | Description                                                     | Type    | Availability                |
|:--------:| --------------------------------------------------------------- | ------- | --------------------------- |
| total    | The total amount of elements available in the collection        | Integer | always                      |
| pageSize | Amount of elements that a response will hold                    | Integer | when paginated              |
| count    | Actual amount of elements in this response                      | Integer | always                      |
| offset   | The page number that is requested from paginated collection     | Integer | when offset based available |
| groups   | Summarized information about aggregation groups                 | Object  | when grouping               |
| totalSums| Aggregations of supported values for elements of the collection | Object  | when showing sums           |

## Links

| Link             | Description                                                              | Availability                |
|:----------------:| ------------------------------------------------------------------------ | --------------------------- |
| self             | Link to the current page in the collection                               | always                      |
| changeSize       | Templated link to change the page size, might change relative position   | when paginated              |
| jumpTo           | Templated link to jump to a specified offset                             | when offset based available |
| nextByOffset     | Link to retrieve the following page of elements (offset based)           | when offset based available |
| previousByOffset | Link to retrieve the preceding page of elements (offset based)           | when offset based available |
| nextByCursor     | Link to retrieve the elements following the current page (cursor based)  | when cursor based available |
| previousByCursor | Link to retrieve the elements preceding the current page (cursor based)  | when cursor based available |

## Offset based pagination [/api/v3/examples{?offset,pageSize}]

Offset based pagination works by specifying two values: the **offset** and the **pageSize**. The page size determines how many items there will
be in a single response at most. The offset determines which page is returned as response, with 1 being the first page (one-indexed).
Note that the server might not allow arbitrarily large page sizes, a client should therefore always check the page size accepted by the server
using the **pageSize** property of the response.

The benefit of offset based pagination is that the total number of pages can be easily determined and that it is possible to jump
to arbitrary pages within the collection. Offset based pagination is therefore well suited when a result is displayed to the end user
in the form of multiple pages anyway.

A drawback of offset based pagination comes with concurrent modification of the collection. If the collection is modified
between two page requests, it is possible that the client receives elements close to the page boundaries twice or does not see them at all.

## view offset based [GET]

+ Parameters
    + offset = `1` (optional, integer, `25`) ... Page number inside the requested collection.

    + pageSize (optional, integer, `25`) ... Number of elements to display per page.

+ Response 200 (application/hal+json)

    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/examples?offset=25&pageSize=25" },
                    "jumpTo": {
                        "href": "/api/v3/examples?offset={offset}&pageSize=25",
                        "templated": true
                    },
                    "changeSize": {
                        "href": "/api/v3/examples?offset=25&pageSize={size}",
                        "templated": true
                    },
                    "previousByOffset": { "href": "/api/v3/examples?offset=0&pageSize=25" },
                    "previousByCursor": { "href": "/api/v3/examples?before=bar&pageSize=25" }
                },
                "_type": "Collection",
                "total": 27,
                "pageSize": 25,
                "count": 2,
                "offset": 25,
                "_embedded": {
                    "elements": [
                        { "foo": "bar" },
                        { "foo": "baz" }
                    ]
                }
            }

## Cursor based pagination [/api/v3/examples{?before,after,pageSize}]

Cursor based pagination is intended to be used, when the client needs a consistent and complete (sub-) range of the collection,
e.g. in infinite scrolling scenarios. In cursor based pagination the client will receive a link to the next and
the previous page in the result set. The guarantee is, that the boundaries of that page will align with the boundaries of the current page,
regardless of changes to the collection.

The drawback for cursor based pagination is, that it is not immediately determinable how many "next" and how many "previous" pages there are.
Cursor based pagination is therefore less suited for use cases where you want to directly "jump" to an arbitrary page.

## view cursor based [GET]

+ Parameters
    + before (optional, string, `bar`) ... Display the elements preceding the given element.
    Note that the value of this parameter is very specific to the collection, a client should not
    try to infer values, but use the **previous** link offered by the collection.

    + after (optional, string, `buz`) ... Display the elements succeeding the given element.
    Note that the value of this parameter is very specific to the collection, a client should not
    try to infer values, but use the **next** link offered by the collection.

    + pageSize (optional, integer, `25`) ... Number of elements to display per page.

+ Response 200 (application/hal+json)

    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/examples?after=buz&pageSize=25" },
                    "changeSize": {
                        "href": "/api/v3/examples?after=buz&pageSize={size}",
                        "templated": true
                    },
                    "previousByCursor": { "href": "/api/v3/examples?before=bar&pageSize=25" }
                },
                "_type": "Collection",
                "total": 27,
                "pageSize": 25,
                "count": 2,
                "_embedded": {
                    "elements": [
                        { "foo": "bar" },
                        { "foo": "baz" }
                    ]
                }
            }

## Aggregations [/api/v3/examples{?groupBy,showSums}]

Collections may support different kinds of aggregations.
Some properties can be summed up. If requested the collection will include the `totalSums` property,
which is a dictionary, where the keys represent the names of the summed properties and the values represent their sums.
Note that you have to mark a column as summable in the instance settings, to be able to retrieve its sums.

It is also possible to group the contents of a collection. In this case:

* the `elements` will be ordered by the specified group key (so that the client receives one group after another)
* The `groups` property will contain a collection of group objects

A group object contains aggregation data for the elements of a group:

### Local Properties

| Property | Description                                                         | Type       | Availability                |
|:--------:| ------------------------------------------------------------------- | ---------- | --------------------------- |
| value    | The value to which the group belongs (e.g. the Status' name)        | String     | always                      |
| count    | Actual amount of elements in this response                          | Integer    | always                      |
| sums     | A dictionary with property sums inside this group (see `totalSums`) | Dictionary | when sums requested         |

## Links

| Link             | Description                                                 | Availability                          |
|:----------------:| ------------------------------------------------------------| ------------------------------------- |
| valueLink        | Link to the corresponding grouping object (e.g. the Status) | only if grouping by a linkable object |

Note that you will always receive a `value`, but only receive a `valueLink` if the grouping was performed
on a linkable property.

## view aggregated result [GET]

+ Parameters
    + groupBy (optional, string, `status`) ... The column to group by.
    Note: Aggregation is as of now only supported by the work package collection.
    You can pass any column name as returned by the [queries](#queries) endpoint.

    + showSums = `false` (optional), boolean, `true` ... Indicates whether properties should be summed up if they support it.

+ Response 200 (application/hal+json)

    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/examples?groupBy=foo&showSums=true" },
                    "changeSize": {
                        "href": "/api/v3/examples?after=buz&pageSize={size}",
                        "templated": true
                    }
                },
                "_type": "Collection",
                "total": 5,
                "pageSize": 25,
                "count": 5,
                "_embedded": {
                    "elements": [
                        { "foo": "bar", "i": 1 },
                        { "foo": "bar", "i": 2 },
                        { "foo": "bar", "i": 3 },
                        { "foo": "baz", "i": 4 },
                        { "foo": "baz", "i": 5 }
                    ],
                    "groups": [
                        {
                            "value : "bar",
                            "count": 3,
                            "sums": {
                                "i": 6
                            }
                        },
                        {
                            "value : "baz",
                            "count": 2,
                            "sums": {
                                "i": 9
                            }
                        }
                    ],
                    "totalSums": {
                        "i": 15
                    }
                }
            }

# Group Root

The root resource contains links to available resources in the API. By following these links
a client should be able to discover further resources in the API.

*Note: Currently there is no list action for projects available.*
*A client will therefore have to know links to projects and can't (yet) discover them.*

| Link                | Description                                      | Type            | Nullable | Supported operations | Condition |
|:-------------------:| ------------------------------------------------ | --------------- | -------- | -------------------- | --------- |
| configuration       | The configuration of this OpenProject instance   | Configuration   |          | READ                 |           |
| user                | The user currently logged-in                     | User            |          | READ                 | logged in |
| userPreferences     | The preferences of the logged-in user            | UserPreference  |          | READ                 | logged in |
| priorities          | List of available priorities                     | Collection      |          | READ                 |           |
| statuses            | List of available work package statuses          | Collection      |          | READ                 |           |
| types               | List of available work package types             | Collection      |          | READ                 |           |
| workPackages        | List of all work packages                        | Collection      |          | READ                 |           |

## Local Properties

| Property                  | Description                                          | Type       | Condition                         | Supported operations |
| :-----------------------: | ---------------------------------------------------- | ---------- | --------------------------------- | -------------------- |
| instanceName              | The name of the OpenProject instance                 | String     |                                   | READ                 |
| coreVersion               | The OpenProject core version number for the instance | String     |                                   | READ                 |

## Root [/api/v3]

+ Model
    + Body

            {
                "_links" : {
                    "configuration" : {
                        "href" : "/api/v3/configuration"
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard - admin"
                    };
                    "userPreferences" : {
                        "href" : "/api/v3/my_preferences"
                    },
                    "priorities" : {
                        "href" : "/api/v3/priorities"
                    },
                    "statuses" : {
                        "href" : "/api/v3/statuses"
                    },
                    "types" : {
                        "href" : "/api/v3/types"
                    },
                    "workPackages" : {
                        "href" : "/api/v3/work_packages"
                    }
                },
                "instanceName" : "My own OpenProject",
                "coreVersion" : "4.3.0"
            }

## View root [GET]

+ Response 200 (application/hal+json)

    [Root][]

# Group Activities

## Local Properties
| Property    | Description      | Type                 | Constraints | Supported operations |
| :---------: | -------------    | ----                 | ----------- | -------------------- |
| id          | Activity id      | Integer              | x > 0       | READ                 |
| version     | Activity version | Integer              | x > 0       | READ                 |
| comment     |                  | Formattable          |             | READ / WRITE         |
| details     |                  | Array of Formattable |             | READ                 |
| createdAt   | Time of creation | DateTime             |             | READ                 |

Activity can be either _type Activity or _type Activity::Comment.

## Activity [/api/v3/activities/{id}]

+ Model
    + Body

            {
                "_type": "Activity::Comment",
                "_links": {
                    "self": {
                        "href": "/api/v3/activity/1",
                        "title": "Priority changed from High to Low"
                    },
                    "workPackage": {
                        "href": "/api/v3/work_packages/1",
                        "title": "quis numquam qui voluptatum quia praesentium blanditiis nisi"
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard - admin"
                    }
                },
                "id": 1,
                "details": [
                    {
                        "format": "textile",
                        "raw": "Lorem ipsum dolor sit amet.",
                        "html": "<p>Lorem ipsum dolor sit amet.</p>"
                    }
                ],
                "comment": {
                    "format": "textile",
                    "raw": "Lorem ipsum dolor sit amet.",
                    "html": "<p>Lorem ipsum dolor sit amet.</p>"
                },
                "createdAt": "2014-05-21T08:51:20Z",
                "version": 31
            }

## View activity [GET]

+ Parameters
    + id (required, integer, `1`) ... Activity id

+ Response 200 (application/hal+json)

    [Activity][]

## Update activity [PATCH]

Updates an activity's comment and, on success, returns the updated activity.

+ Parameters
    + id (required, integer, `1`) ... Activity id

+ Request (application/json)

        {
          "comment": { "raw": "The updated comment" }
        }

+ Response 200 (application/hal+json)

    [Activity][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit journals

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to edit the comment of this journal entry."
            }


+ Response 422 (application/hal+json)

    Returned if the client tries to modify a read-only property.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyIsReadOnly",
                "message": "The ID of an activity can't be changed."
            }

# Group Attachments

Attachments are files that were uploaded to OpenProject. Each attachment belongs to a single
container (e.g. a work package or a board message).

## Actions

| Link                | Description                                                          | Condition                                    |
|:-------------------:|----------------------------------------------------------------------| -------------------------------------------- |
| delete              | Deletes this attachment                                              | **Permission**: edit on attachment container |

## Linked Properties
|  Link            | Description                                         | Type          | Constraints | Supported operations |
|:----------------:| --------------------------------------------------- | ------------- | ----------- | -------------------- |
| self             | This attachment                                     | Attachment    | not null    | READ                 |
| container        | The object (e.g. WorkPackage) housing the attachment| Anything      | not null    | READ                 |
| author           | The user who uploaded the attachment                | User          | not null    | READ                 |
| downloadLocation | Direct download link to the attachment              | -             | not null    | READ                 |

## Local Properties
| Property     | Description                                     | Type        | Constraints | Supported operations |
|:------------:| ----------------------------------------------- | ----------- | ----------- | -------------------- |
| id           | Attachment's id                                 | Integer     | x > 0       | READ                 |
| fileName     | The name of the uploaded file                   | String      | not null    | READ                 |
| fileSize     | The size of the uploaded file in Bytes          | Integer     | x >= 0      | READ                 |
| description  | A user provided description of the file         | Formattable | not null    | READ                 |
| contentType  | The files MIME-Type as determined by the server | String      | not null    | READ                 |
| digest       | A checksum for the files content                | Digest      | not null    | READ                 |
| createdAt    | Time of creation                                | DateTime    | not null    | READ                 |

## Attachment [/api/v3/attachments/{id}]

+ Model
    + Body

            {
                "_type": "Attachment",
                "_links": {
                    "self": {
                        "href": "/api/v3/attachments/1"
                    },
                    "container" {
                        "href": "/api/v3/work_packages/1"
                    },
                    "author": {
                        "href": "/api/v3/users/1"
                    },
                    "downloadLocation": {
                        "href": "/attachments/1/download"
                    }
                },
                "id": 1,
                "fileName": "cat.png",
                "filesize": 24,
                "description": {
                    "format": "plain",
                    "raw": "A picture of a cute cat",
                    "html": "<p>A picture of a cute cat</p>"
                },
                "contentType": "image/png",
                "digest": {
                    "algorithm": "md5",
                    "64c26a8403cd796ea4cf913cda2ee4a9":
                },
                "createdAt": "2014-05-21T08:51:20Z"
            }

## View attachment [GET]

+ Parameters
    + id (required, integer, `1`) ... Attachment id

+ Response 200 (application/hal+json)

    [Attachment][]

+ Response 404 (application/hal+json)

    Returned if the attachment does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view permission for the container of the attachment

    *Note: A client without sufficient permissions shall not be able to test for the existence of an attachment.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified attachment does not exist."
            }

## Delete attachment [DELETE]

Permanently deletes the specified attachment.

+ Parameters
    + id (required, integer, `1`) ... Attachment id

+ Response 204

    Returned if the attachment was deleted successfully.

    Note that the response body is empty as of now. In future versions of the API a body
    *might* be returned along with an appropriate HTTP status.

    + Body

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit permission for the container of the attachment

    *Note that you will only receive this error, if you are at least allowed to see the attachment.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to delete this attachment."
            }

+ Response 404 (application/hal+json)

    Returned if the attachment does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view permission for the container of the attachment

    *Note: A client without sufficient permissions shall not be able to test for the existence of an attachment.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified attachment does not exist."
            }

# Attachments by work package [/api/v3/work_packages/{id}/attachments]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages/1/attachments" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_type": "Attachment",
                            "_links": {
                                "self": {
                                    "href": "/api/v3/attachments/1"
                                },
                                "container" {
                                    "href": "/api/v3/work_packages/1"
                                },
                                "author": {
                                    "href": "/api/v3/users/1"
                                },
                                "downloadLocation": {
                                    "href": "/attachments/1/download"
                                }
                            },
                            "id": 1,
                            "fileName": "cat.png",
                            "filesize": 24,
                            "description": {
                                "format": "plain",
                                "raw": "A picture of a cute cat",
                                "html": "<p>A picture of a cute cat</p>"
                            },
                            "contentType": "image/png",
                            "digest": {
                                "algorithm": "md5",
                                "64c26a8403cd796ea4cf913cda2ee4a9":
                            },
                            "createdAt": "2014-05-21T08:51:20Z"
                        },
                        {
                            "_type": "Attachment",
                            "_links": {
                                "self": {
                                    "href": "/api/v3/attachments/2"
                                },
                                "container" {
                                    "href": "/api/v3/work_packages/1"
                                },
                                "author": {
                                    "href": "/api/v3/users/1"
                                },
                                "downloadLocation": {
                                    "href": "/attachments/2/download"
                                }
                            },
                            "id": 2,
                            "fileName": "cat2.png",
                            "filesize": 24,
                            "description": {
                                "format": "plain",
                                "raw": "A picture of another cute cat",
                                "html": "<p>A picture of another cute cat</p>"
                            },
                            "contentType": "image/png",
                            "digest": {
                                "algorithm": "md5",
                                "46c26a8403cd769ea4c9f13cdae2e49a":
                            },
                            "createdAt": "2014-05-21T08:51:20Z"
                        }
                    ]
                }
            }

## List attachments [GET]

+ Parameters
    + id (required, integer, `1`) ... ID of the work package whose attachments will be listed

+ Response 200 (application/hal+json)

    [Attachments by work package][]

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work package

    *Note: A client without sufficient permissions shall not be able to test for the existence of a work package.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Add attachment [POST]

To add an attachment to a work package, a client needs to issue a request of type `multipart/form-data`
with exactly two parts.

The first part *must* be called `metadata`. Its content type is expected to be `application/json`,
the body *must* be a single JSON object, containing at least the `fileName` and optionally the attachments `description`.

The second part *must* be called `file`, its content type *should* match the mime type of the file.
The body *must* be the raw content of the file.
Note that a `filename` must be indicated in the `Content-Disposition` of this part, however it will be ignored.
Instead the `fileName` inside the JSON of the metadata part will be used.

+ Parameters
    + id (required, integer, `1`) ... ID of the work package to receive the attachment

+ Request (multipart/form-data)

        --boundary-delimiter
        Content-Disposition: form-data; name="metadata"
        Content-Type: application/json; charset=UTF-8

        {
          "fileName": "cute-cat.png",
          "description": {
            "raw": "A cute kitty, cuddling with its friends!"
          }
        }

        --boundary-delimiter
        Content-Disposition: form-data; name="file"; filename="attachment"
        Content-Type: image/png

        PNG file data
        --boundary-delimiter--

+ Response 200 (application/hal+json)

    [Attachment][]

+ Response 400 (application/hal+json)

    Returned if the client sends a not understandable request. Reasons include:

    * Omitting one of the required parts (metadata and file)
    * sending unparsable JSON in the metadata part

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request could not be parsed as JSON."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit work package or add work package

    *Note that you will only receive this error, if you are at least allowed to see the work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to delete this attachment."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work package

    *Note: A client without sufficient permissions shall not be able to test for the existence of a work package.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

+ Response 422 (application/hal+json)

    Returned if the client tries to send an invalid attachment.
    Reasons are:

    * Omitting the file name (`fileName` property of metadata part)
    * Sending a file that is too large

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                "message": "File is too large (maximum size is 5242880 Bytes)."
            }

# Group Categories

## Linked Properties
|  Link           | Description                                         | Type          | Constraints | Supported operations |
|:---------------:| --------------------------------------------------- | ------------- | ----------- | -------------------- |
| self            | This category                                       | Category      | not null    | READ                 |
| project         | The project of this category                        | Project       | not null    | READ                 |
| defaultAssignee | Default assignee for work packages of this category | User          |             | READ                 |

## Local Properties
| Property   | Description   | Type    | Constraints | Supported operations |
| :--------: | ------------- | ------- | ----------- | -------------------- |
| id         | Category id   | Integer | x > 0       | READ                 |
| name       | Category name | String  |             | READ                 |

## Categories by Project [/api/v3/projects/{project_id}/categories]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/11/categories" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_links": {
                                "self": {
                                    "href": "/api/v3/categories/10",
                                    "title": "Category with assignee"
                                },
                                "project": {
                                    "href": "/api/v3/projects/11",
                                    "title": "Example project"
                                },
                                "defaultAssignee": {
                                    "href": "/api/v3/users/42",
                                    "title": "John Sheppard"
                                }
                            },
                            "_type": "Category",
                            "id": 10,
                            "name": "Foo"
                        },
                        {
                            "_links": {
                                "self": { "href": "/api/v3/categories/11" },
                                "project": { "href": "/api/v3/projects/11" }
                            },
                            "_type": "Category",
                            "id": 11,
                            "name": "Bar"
                        }
                    ]
                }
            }

## List categories of a project [GET]

+ Parameters
    + project_id (required, integer, `1`) ... ID of the project whoose categories will be listed

+ Response 200 (application/hal+json)

    [Categories by Project][]

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view project

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Category [/api/v3/categories/{id}]

+ Model
    + Body

            {
                "_links": {
                    "self": {
                        "href": "/api/v3/categories/10",
                        "title": "Category with assignee"
                     },
                    "project": {
                        "href": "/api/v3/projects/11",
                        "title": "Example project"
                    },
                    "defaultAssignee": {
                        "href": "/api/v3/users/42",
                        "title": "John Sheppard"
                    }
                },
                "_type": "Category",
                "id": 10,
                "name": "Foo"
            }

## View Category [GET]

+ Parameters
    + id (required, integer, `1`) ... category id

+ Response 200 (application/hal+json)

    [Category][]

+ Response 404 (application/hal+json)

    Returned if the category does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view project (defining the category)

    *Note: A client without sufficient permissions shall not be able to test for the existence of
    a category. That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified category does not exist."
            }

# Group Configuration

The configuration endpoint allows to read certain configuration parameters of the OpenProject instance.
Note that there is no 1:1 relationship between this endpoint and the settings you can find in your settings.yml.

For now this endpoint will only allow access to settings deemed useful for a client to know in general.

| Link                | Description                                      | Type          | Nullable | Supported operations |
|:-------------------:| ------------------------------------------------ | ------------- | -------- | -------------------- |
| self                | The configuration                                | Configuration |          | READ                 |

## Local Properties
| Property                  | Description                                        | Type       | Condition                         | Supported operations |
| :-----------------------: | -------------------------------------------------- | ---------- | --------------------------------- | -------------------- |
| maximumAttachmentFileSize | The maximum allowed size of an attachment in Bytes | Integer    |                                   | READ                 |
| perPageOptions            | Page size steps to be offered in paginated list UI | Integer[]  |                                   | READ                 |

## Configuration [/api/v3/configuration]

+ Model
    + Body

            {
                "_type": "Configuration",
                "_links": {
                    "href": "/api/v3/configuration"
                },
                "maximumAttachmentFileSize": 5242880,
                "perPageOptions": [1, 10, 100]
            }

## View configuration [GET]

+ Response 200 (application/hal+json)

    [Configuration][]

# Group Forms

This API provides forms as a concept to aid in editing or creating resources. The goal of forms is to:

* make writable properties of a resource discoverable
* show to which values a property can be set
* validate changes to a resource and indicate validation errors

These benefits aside, a client can freely choose to immediately edit a resource without prior validation by a form.
In the case of an invalid request the edit will fail and return appropriate errors nevertheless.

A form is associated to a single resource and aids in performing changes on that resource.
When posting to a form endpoint with an empty request body or an empty JSON object,
you will receive an initial form for the associated resource.
Subsequent calls to the form should contain a single JSON object as described by the form.

## Actions

| Link                | Description                                                           | Condition                        |
|:-------------------:| --------------------------------------------------------------------- | -------------------------------- |
| validate            | Validate changes, show errors and allowed values for changed resource |                                  |
| commit              | Actually perform changes to the resource                              | form content is valid            |
| previewMarkup       | Post markup (e.g. textile) here to receive an HTML-rendered response  |                                  |

## Linked Properties

| Link                | Description                                      | Type          | Nullable | Supported operations |
|:-------------------:| ------------------------------------------------ | ------------- | -------- | -------------------- |
| self                | This form                                        | Form          |          | READ                 |

## Embedded Properties:

Apart from the linked properties, forms contain always three other embedded properties:

* `payload`
* `schema`
* `validationErrors`

Their purpose is explained below.

### Payload

The payload contains an edited version of the resource that will be modified when commiting the form.
This representation contains all writable properties of the resource and reflects all changes that the latest call to **validate** included,
thereby acting as a preview for the changes.

In case the client tries to set the value to something invalid, the invalid change is also reflected here. However a validation error (see below)
indicates that a commit of this payload would fail.

It might happen that setting one property affects the allowed values for another property. Thus by changing a property A
the current value of another property B might become invalid. If the client did not yet touch the value of B, the payload will
contain a default value for that property. Nevertheless the client will also receive an apropriate validation error for value B.

The content of this element *can* be used as a template for the request body of a call to **validate** or **commit**.

A call to **validate** and **commit** does not need to include all properties that were defined in the `payload` section.
It is only necessary to include the properties that you want to change, as well as the `lockVersion` if one is present.
However you *may* include all the properties sent in the `payload` section.

### Schema

The schema embedded in a form is a normal [schema describing the underlying resource](#schema).
However, the embedded schema can change with each revalidation of the form.
For example it might be possible, that changing the type of a work package affects its available properties,
as well as possible values for certain properties.
As this makes the embedded schema very dynamic, it is not included as a static link.

### Validation Errors

Like a [schema](#schema) the validation errors build a dictionary where the key is a property name.
Each value is an error object that indicates the error that occured validating the corresponding property.
There are only key value pairs for properties that failed validation, the element is empty if all validations succeeded.

However note that even in the case of validation errors, the response you receive from the form endpoint will be an HTTP 200.
That is because the main purpose of a form is helping the client to sort out validation errors.

## Example Form [/api/v3/example/form]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/example/form" },
                    "validate": {
                        "href": "/api/v3/example/form",
                        "method": "POST"
                    },
                    "previewMarkup": {
                        "href": "/api/v3/render/textile",
                        "method": "POST"
                    },
                    "commit": {
                        "href": "/api/v3/example",
                        "method": "PATCH"
                    }
                },

                "_type": "Form",

                "_embedded": {
                    "payload": {
                        "_links": {
                            "status": { "href": "/api/v3/statuses/1" }
                        },
                        "_type": "Example",
                        "lockVersion": 5,
                        "subject": "An example title"
                    },
                    "schema": {
                        "_type": "Schema",
                        "_links": {
                            "self": { "href": "/api/v3/example/schema" }
                        },

                        "lockVersion": {
                            "type": "Integer",
                            "writable": false
                        },
                        "subject": {
                            "type": "String",
                            "minLength": 1,
                            "maxLength": 255
                        },
                        "status": {
                            "_links": {
                                "allowedValues": [
                                    { "href": "/api/v3/statuses/1", "title": "New" },
                                    { "href": "/api/v3/statuses/2", "title": "Closed" }
                                ]
                            },

                            "type": "Status",

                            "_embedded": {
                                "allowedValues": [
                                    {
                                        "_links": { "self": { "href": "/api/v3/statuses/1" } },
                                        "_type": "Status",
                                        "id": 1,
                                        "name": "New",
                                        "position": 1,
                                        "isDefault": true,
                                        "isClosed": false,
                                        "defaultDoneRatio": 0,
                                        "createdAt": "2014-05-21T08:51:20Z",
                                        "updatedAt": "2014-05-21T09:12:00Z"
                                    },
                                    {
                                        "_links": { "self": { "href": "/api/v3/statuses/2" } },
                                        "_type": "Status",
                                        "id": 2,
                                        "name": "Closed",
                                        "position": 2,
                                        "isDefault": false,
                                        "isClosed": true,
                                        "defaultDoneRatio": 100,
                                        "createdAt": "2014-05-21T08:51:20Z",
                                        "updatedAt": "2014-05-21T09:12:00Z"
                                    }
                                ]
                            }
                        }
                    },
                    "validationErrors": {
                        "subject": {
                            "_type": "Error",
                            "errorIdentifier": "urn:openproject-org:api:v3:errors:BadExampleError",
                            "message": "For the purpose of this example we need a validation error. The remainder of the response pretends there were no errors."
                        }
                    }
                }
            }

## show or validate form [POST]

This is an example of how a form might look like. Note that this endpoint does not exist in the actual implementation.

+ Request (application/json)

        {
            "lockVersion": 5,
            "_type": "Example",
            "subject": "An example title"
        }

+ Response 200 (application/hal+json)

    [Example Form][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body and the request body
    was not empty.

    Note that this error only occurs when the content is not at all a single JSON object.
    It **does not occur** for requests containing undefined properties or invalid property values.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was neither empty, nor did it contain a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions to modify the associated resource.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to edit example resources."
            }

+ Response 409 (application/hal+json)

    Returned if underlying resource was changed since the client requested the form. This is determined using the `lockVersion` property.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:UpdateConflict",
                "message": "The resource you are about to edit was changed in the meantime."
            }

# Group Previewing

Throughout OpenProject user input for many properties can be formatted (e.g. using *Textile*).
Using the appropriate rendering endpoint it is possible to render custom formatted inputs into HTML and thus
receive a preview of the rendered text.

The request to a rendering endpoint must always have a MIME-Type of `text/plain`.
The request body is the actual string that shall be rendered as HTML string.

## Textile [/api/v3/render/textile{?context}]

+ Model
    + Body

            <p>Hello world! <a href="http://example.com">This</a> <strong>is</strong> textile!</p>

## Preview Textile document [POST]

+ Parameters
    + context (optional, string, `/api/v3/work_packages/42`)
        API-Link to the context in which the rendering occurs, for example a specific work package.

        If left out only context-agnostic rendering takes place.
        Please note that OpenProject features textile-extensions that can only work given a context (e.g. display attached images).

        **Supported contexts:**

        * `/api/v3/work_packages/{id}` - an existing work package

+ Request (text/plain)

            Hello world! "This":http://example.com *is* textile!

+ Response 200 (text/html)

    [Textile][]

+ Response 400 (application/json)

    Returned if the context passed by the client is not valid (e.g. unknown).

    Note that this response will also occur when the requesting user
    is not allowed to see the context resource (e.g. limited work package visibility).

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRenderContext",
                "message": "Could not render textile string in the given context."
            }

+ Response 415 (application/json)

    Returned if the Content-Type indicated in the request is not `text/plain`.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:TypeNotSupported",
                "message": "Expected Content-Type to be 'text/plain' but got 'application/json'."
            }

## Plain Text [/api/v3/render/plain]

+ Model
    + Body

            <p>Hello world! This *is* plain text!</p>

## Preview plain document [POST]

+ Request (text/plain)

            Hello world! This *is* plain text!

+ Response 200 (text/html)

    [Plain Text][]

+ Response 415 (application/json)

    Returned if the Content-Type indicated in the request is not `text/plain`.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:TypeNotSupported",
                "message": "Expected Content-Type to be 'text/plain' but got 'application/json'."
            }

# Group Priorities

## Linked Properties
|  Link     | Description                                 | Type          | Constraints           | Supported operations |
|:---------:|-------------------------------------------- | ------------- | --------------------- | -------------------- |
| self      | This priority                               | Priority      | not null              | READ                 |

## Local Properties
| Property    | Description                                 | Type       | Constraints | Supported operations |
| :---------: | ------------------------------------------- | ---------- | ----------- | -------------------- |
| id          | Priority id                                 | Integer    | x > 0       | READ                 |
| name        | Priority name                               | String     | not empty   | READ                 |
| position    | Sort index of the priority                  | Integer    | x > 0       | READ                 |
| isDefault   | Indicates whether this is the default value | Boolean    |             | READ                 |
| isActive    | Indicates whether the priority is available | Boolean    |             | READ                 |

## Priorities [/api/v3/priorities]

+ Model
    + Body

            {
                "_links" : {
                    "self" : {
                        "href" : "/api/v3/priorities"
                    }
                },
                "_type" : "Collection",
                "total" : 4,
                "count" : 4,
                "_embedded" : {
                    "elements" : [{
                            "_type" : "Priority",
                            "_links" : {
                                "self" : {
                                    "href" : "/api/v3/priorities/1",
                                    "title" : "Low"
                                }
                            },
                            "id" : 1,
                            "name" : "Low",
                            "position" : 1,
                            "isDefault" : false,
                            "isActive" : true
                        }, {
                            "_type" : "Priority",
                            "_links" : {
                                "self" : {
                                    "href" : "/api/v3/priorities/2",
                                    "title" : "Normal"
                                }
                            },
                            "id" : 2,
                            "name" : "Normal",
                            "position" : 2,
                            "isDefault" : true,
                            "isActive" : true
                        }, {
                            "_type" : "Priority",
                            "_links" : {
                                "self" : {
                                    "href" : "/api/v3/priorities/3",
                                    "title" : "High"
                                }
                            },
                            "id" : 3,
                            "name" : "High",
                            "position" : 3,
                            "isDefault" : false,
                            "isActive" : true
                        }, {
                            "_type" : "Priority",
                            "_links" : {
                                "self" : {
                                    "href" : "/api/v3/priorities/4",
                                    "title" : "Immediate"
                                }
                            },
                            "id" : 4,
                            "name" : "Immediate",
                            "position" : 5,
                            "isDefault" : false,
                            "isActive" : true
                        }
                    ]
                }
            }


## List all Priorities [GET]

+ Response 200 (application/hal+json)

    [Priorities][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the priorities."
            }

## Priority [/api/v3/priorities/{id}]

+ Model
    + Body

            {
                "_type" : "Priority",
                "_links" : {
                    "self" : {
                        "href" : "/api/v3/priorities/1",
                        "title" : "Low"
                    }
                },
                "id" : 1,
                "name" : "Low",
                "position" : 1,
                "isDefault" : false,
                "isActive" : true
            }


## view Priority [GET]

+ Parameters
    + id (required, integer, `1`) ... Priority id

+ Response 200 (application/hal+json)

    [Priority][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see this priority."
            }

# Group Projects

## Actions

| Link                       | Description                                                          | Condition                         |
|:--------------------------:|----------------------------------------------------------------------| --------------------------------- |
| createWorkPackage          | Form endpoint that aids in preparing and creating a work package     | **Permission**: add work packages |
| createWorkPackageImmediate | Directly creates a work package in the project                       | **Permission**: add work packages |

## Linked Properties

| Link         | Description                          | Type       | Constraints | Supported operations |
| :----------: | -------------                        | ----       | ----------- | -------------------- |
| self         | This project                         | Project    | not null    | READ                 |
| categories   | Categories available in this project | Collection | not null    | READ                 |
| types        | Types available in this project      | Collection | not null    | READ                 |
| versions     | Versions available in this project   | Collection | not null    | READ                 |
| workPackages | Work Packages of this project        | Collection | not null    | READ                 |

## Local Properties

| Property    | Description                                   | Type     | Constraints | Supported operations |
| :---------: | -------------                                 | ----     | ----------- | -------------------- |
| id          | Projects's id                                 | Integer  | x > 0       | READ                 |
| identifier  |                                               | String   |             | READ                 |
| name        |                                               | String   |             | READ                 |
| description |                                               | String   |             | READ                 |
| createdAt   | Time of creation                              | DateTime |             | READ                 |
| updatedAt   | Time of the most recent change to the project | DateTime |             | READ                 |

## Project [/api/v3/projects/{id}]

+ Model
    + Body

            {
                "_type": "Project",
                "_links": {
                    "self": {
                        "href": "/api/v3/projects/1",
                        "title": "Lorem"
                    },
                    "createWorkPackage": {
                        "href": "/api/v3/projects/1/work_packages/form",
                        "method": "post"
                    },
                    "createWorkPackageImmediate": {
                        "href": "/api/v3/projects/1/work_packages",
                        "method": "post"
                    },
                    "categories": { "href": "/api/v3/projects/1/categories" },
                    "types": { "href": "/api/v3/projects/1/types" },
                    "versions": { "href": "/api/v3/projects/1/versions" },
                    "workPackages": { "href": "/api/v3/projects/1/work_packages" }
                },
                "id": 1,
                "identifier": "project_identifier",
                "name": "Project example",
                "description": "Lorem ipsum dolor sit amet",
                "createdAt": "2014-05-21T08:51:20Z",
                "updatedAt": "2014-05-21T08:51:20Z"
            }

## View project [GET]

+ Parameters
    + id (required, integer, `1`) ... Project id

+ Response 200 (application/hal+json)

    [Project][]

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view project

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Projects by version [/api/v3/versions/{id}/projects]

+ Model
    + Body

            {
                "_links":
                {
                    "self":
                    {
                        "href": "/api/v3/versions/2/projects"
                    }
                },
                "total": 1,
                "count": 1,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_type": "Project",
                            "_links": {
                                "self": {
                                    "href": "/api/v3/projects/1",
                                    "title": "Lorem"
                                },
                                "categories": { "href": "/api/v3/projects/1/categories" },
                                "versions": { "href": "/api/v3/projects/1/versions" }
                            },
                            "id": 1,
                            "identifier": "project_identifier",
                            "name": "Project example",
                            "description": "Lorem ipsum dolor sit amet",
                            "createdAt": "2014-05-21T08:51:20Z",
                            "updatedAt": "2014-05-21T08:51:20Z"
                        }
                    ]
                }
            }

## List projects with version [GET]

This endpoint lists the projects where the given version is available.

The projects returned depend on the sharing settings of the given version,
but are also limited to the projects that the current user is allowed to see.

+ Parameters
    + id (required, integer, `1`) ... Version id

+ Response 200 (application/hal+json)

    [Projects by version][]

+ Response 404 (application/hal+json)

    Returned if the version does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work packages **or** manage versions (any project where the given version is available)

    *Note: A client without sufficient permissions shall not be able to test for the existence of a version.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified version does not exist."
            }

## Work Package Columns [/api/v3/projects/{id}/work_packages/columns]

## View Work Package columns [GET]

Lists the columns available for work packages of this project in the form of field schemas.

+ Parameters
    + id (required, integer, `1`) ... Project id

+ Response 200 (application/hal+json)

    [Example Schema][]

+ Response 403 (application/hal+json)

    Returned if the client is not allowed to see the available columns of work packages on this
    project.

    **Required permission:** view work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see work packages of this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }


# Group Queries

| Link               | Description                                                              | Type         | Constraints  | Supported operations  | Condition                                 |
| :----------------: | ------------------------------------------------------------------------ | ------------ | ------------ | --------------------- | ----------------------------------------- |
| self               | This query                                                               | Query        | not null     | READ                  |                                           |
| user               | The user that owns this query                                            | User         | not null     | READ                  |                                           |
| project            | The project on which this query operates                                 | Project      |              | READ                  |                                           |

## Local Properties

| Property         | Description                                            | Type        | Constraints                      | Supported operations |
| :--------------: | ------------------------------------------------------ | ----------- | -------------------------------- | -------------------- |
| id               | Query id                                               | Integer     | x > 0                            | READ                 |
| name             | Query name                                             | String      |                                  | READ                 |
| filters          | An object describing the queries filter conditions     | Object      |                                  | READ                 |
| columnNames      | Ordered list of properties to be shown in this query   | String[]    |                                  | READ                 |
| sortCriteria     | An object describing the sorting rules of this query   | Object      |                                  | READ                 |
| groupBy          | The property to group results of this query by         | String      |                                  | READ                 |
| displaySums      | Should sums (of supported properties) be shown?        | Boolean     |                                  | READ                 |
| isPublic         | Can users besides the owner see the query?             | Boolean     |                                  | READ                 |
| isStarred        | Should the query be highlighted to the user?           | Boolean     |                                  | READ                 |

## Query [/api/v3/queries/{id}]

+ Model
    + Body

            {
                "_type": "Query",
                "_links": {
                    "self": {
                        "href": "/api/v3/queries/2",
                        "title": "My work packages"
                    },
                    "project": {
                        "href": "/api/v3/projects/1",
                        "title": "A project"
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard"
                    }
                },
                "id": 2,
                "name": "My work packages",
                "filters": [
                    {
                        "status": {
                            "operator": "o",
                            "values": null
                        }
                    },
                    {
                        "assignee": {
                            "operator": "=",
                            "values": [
                                "me"
                            ]
                        }
                    }
                ],
                "isPublic": false,
                "columnNames": [
                    "type",
                    "status",
                    "priority",
                    "subject",
                    "assignee"
                ],
                "sortCriteria": [
                    [
                        "parent",
                        "desc"
                    ]
                ],
                "groupBy": null,
                "displaySums": false,
                "isStarred": true
            }

## View query [GET]

*might be subject to change in the future*

+ Parameters
    + id (required, integer, `1`) ... Query id

+ Response 200 (application/hal+json)

    [Query][]

+ Response 404 (application/hal+json)

    Returned if the query does not exist or the client does not have sufficient permissions to see it.

    **Required condition:** query belongs to user or query is public

    **Required permission:** view work package in queries project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified query does not exist."
            }

## Star Query [/api/v3/queries/{id}/star]

+ Model
    + Body

            {
                "_type": "Query",
                "_links": {
                    "self": {
                        "href": "/api/v3/queries/2",
                        "title": "My work packages"
                    },
                    "project": {
                        "href": "/api/v3/projects/1",
                        "title": "Lorem ipsum"
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard - admin"
                    }
                },
                "id": 2,
                "name": "My work packages",
                "filters": [
                    {
                        "status": {
                            "operator": "o",
                            "values": null
                        }
                    },
                    {
                        "assignee": {
                            "operator": "=",
                            "values": [
                                "me"
                            ]
                        }
                    }
                ],
                "isPublic": "false",
                "columnNames": [
                    "type",
                    "status",
                    "priority",
                    "subject",
                    "assignee"
                ],
                "sortCriteria": [
                    [
                        "parent",
                        "desc"
                    ]
                ],
                "groupBy": null,
                "displaySums": "false",
                "isStarred": true
            }

## Star query [PATCH]

+ Parameters
    + id (required, integer, `1`) ... Query id

+ Response 200 (application/hal+json)

    [Star Query][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send an empty request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not empty."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** for own queries none; for public queries: manage public queries

    *Note that you will only receive this error, if you are at least allowed to see the corresponding query.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to star this query."
            }

+ Response 404 (application/hal+json)

    Returned if the query does not exist or the client does not have sufficient permissions to see it.

    **Required condition:** query belongs to user or query is public

    **Required permission:** view work package in queries project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified query does not exist."
            }

## Unstar Query [/api/v3/queries/{id}/unstar]

+ Model
    + Body

            {
                "_type": "Query",
                "_links": {
                    "self": {
                        "href": "/api/v3/queries/2",
                        "title": "My work packages"
                    },
                    "project": {
                        "href": "/api/v3/projects/1",
                        "title": "Lorem ipsum"
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard - admin"
                    }
                },
                "id": 2,
                "name": "My work packages",
                "filters": [
                    {
                        "status": {
                            "operator": "o",
                            "values": null
                        }
                    },
                    {
                        "assignee": {
                            "operator": "=",
                            "values": [
                                "me"
                            ]
                        }
                    }
                ],
                "isPublic": "false",
                "columnNames": [
                    "type",
                    "status",
                    "priority",
                    "subject",
                    "assignee"
                ],
                "sortCriteria": [
                    [
                        "parent",
                        "desc"
                    ]
                ],
                "groupBy": null,
                "displaySums": "false",
                "isStarred": "false"
            }

## Unstar query [PATCH]

+ Parameters
    + id (required, integer, `1`) ... Query id

+ Response 200 (application/hal+json)

    [Unstar Query][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send an empty request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not empty."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** for own queries none; for public queries: manage public queries

    *Note that you will only receive this error, if you are at least allowed to see the corresponding query.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to unstar this query."
            }

+ Response 404 (application/hal+json)

    Returned if the query does not exist or the client does not have sufficient permissions to see it.

    **Required condition:** query belongs to user or query is public

    **Required permission:** view work package in queries project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified query does not exist."
            }

# Group Revisions

Revisions are sets of updates to files in the context of repositories linked in OpenProject.

## Linked Properties
|  Link            | Description                                                                                       | Type          | Constraints | Supported operations |
|:----------------:| --------------------------------------------------------------------------------------------------| ------------- | ----------- | -------------------- |
| self             | This revision                                                                                     | Revision      | not null    | READ                 |
| project          | The project to which the revision belongs                                                         | Project       | not null    | READ                 |
| author           | The user that added this revision, if the authorName was mapped to a user in OpenProject          | User          |             | READ                 |
| showRevision     | A URL to the repository view (outside APIv3) showing this revision                                | -             | not null    | READ                 |


## Local Properties
| Property                | Description                                                                                                                                                 | Type        | Constraints | Supported operations |
|:-----------------------:| ------------------------------------------------------------------------------------------------------------------------------------------------------------| ----------- | ----------- | -------------------- |
| id                      | Revision's id, assigned by OpenProject                                                                                                                      | Integer     | x > 0       | READ                 |
| identifier              | The raw SCM identifier of the revision (e.g. full SHA hash)                                                                                                 | String      | not null    | READ                 |
| formattedIdentifier     | The SCM identifier of the revision, formatted (e.g. shortened unambiguous SHA hash). May be identical to identifier in many cases                           | String      | not null    | READ                 |
| authorName              | The name of the author that committed this revision. Note that this name is retrieved from the repository and does not identify a user in OpenProject.      | String      | not null    | READ                 |
| message                 | The commit message of the revision                                                                                                                          | Formattable | not null    | READ                 |
| createdAt               | The time this revision was committed to the repository                                                                                                      | DateTime    | not null    | READ                 |

## Revision [/api/v3/revisions/{id}]

+ Model
    + Body

            {
                "_type": "Revision",
                "_links": {
                    "self": {
                        "href": "/api/v3/revisions/1"
                    },
                    "project" {
                        "href": "/api/v3/projects/1"
                    },
                    "author": {
                        "href": "/api/v3/users/1"
                    },
                    "showRevision": {
                        "href": "/projects/identifier/repository/revision/11f4b07"
                    }
                },
                "id": 1,
                "identifier": "11f4b07dff4f4ce9548a52b7d002daca7cd63ec6",
                "formattedIdentifier": "11f4b07",
                "authorName": "Some Developer",
                "message": {
                    "format": "plain",
                    "raw": "This revision provides new features\n\nAn elaborate description",
                    "html": "<p>This revision provides new features<br/><br/>An elaborate description</p>"
                },
                "createdAt": "2015-07-21T13:36:59Z"
            }

## View revision [GET]

+ Parameters
    + id (required, integer, `1`) ... Revision id

+ Response 200 (application/hal+json)

    [Revision][]

+ Response 404 (application/hal+json)

    Returned if the revision does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view changesets for the project the repository is created in.

    *Note: A client without sufficient permissions shall not be able to test for the existence of a revision.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified revision does not exist."
            }

# Group Schemas

## Linked Properties

| Link                | Description                              | Type          | Nullable | Supported operations |
|:-------------------:| ---------------------------------------- | ------------- | -------- | -------------------- |
| self                | This schema                              | Schema        |          | READ                 |

The schema provides more detailed information about the properties of a resource.
The schema is represented by a dictionary containing names of resource properties as keys
and objects describing the corresponding property as values.
These objects are called **field schema** and form the core of the schema representation,
each of them can contain its own `_links` and `_embedded` section.

# Field schema

## Linked Properties

| Property       | Description                                                    |
|:--------------:| -------------------------------------------------------------- |
| allowedValues  | List of resources that are assignable by the current user.     |

The `allowedValues` can either contain a list of canonical links or just a single link to a collection resource.
This is an optimization to allow efficient handling of both small resource lists (that can be enumerated inline) and large
resource lists (requiring one or more separate requests).

## Local Properties

| Property          | Description                                                                        | Type     | Default |
|:-----------------:| ---------------------------------------------------------------------------------- | -------- | ------- |
| name              | Human readable name of the property as it could be displayed in a UI               | String   |         |
| type              | The data type of the properties values                                             | MetaType |         |
| minLength         | The value of the property must at least contain the specified amount of characters | Integer  | 0       |
| maxLength         | The value of the property must at most contain the specified amount of characters  | Integer  | ∞       |
| regularExpression | The value of the property must match the given regular expression (if not null)    | String   | null    |
| required          | If true this property is not nullable                                              | Boolean  | true    |
| writable          | If false it is not allowed to **change** the properties value                      | Boolean  | true    |

All of the above properties that do not have a default value *must* be present in the schema.
For properties that have a default value, the client can assume the default value, if the property is missing.

Note that regular expressions used in the API follow the rules of [Ruby Regular Expressions](http://www.ruby-doc.org/core-2.1.5/Regexp.html).

## Example Schema [/api/v3/example/schema]

+ Model
    + Body

            {
                "_type": "Schema",
                "_links": {
                    "self": { "href": "/api/v3/example/schema" }
                },

                "lockVersion": {
                    "name": "Resource Version",
                    "type": "Integer",
                    "writable": false
                },
                "subject": {
                    "name": "Subject",
                    "type": "String",
                    "minLength": 1,
                    "maxLength": 255
                },
                "status": {
                    "_links": {
                        "allowedValues": [
                            { "href": "/api/v3/statuses/1", "title": "New" },
                            { "href": "/api/v3/statuses/2", "title": "Closed" }
                        ]
                    },

                    "name": "Status",
                    "type": "Status",

                    "_embedded": {
                        "allowedValues": [
                            {
                                "_links": { "self": { "href": "/api/v3/statuses/1" } },
                                "_type": "Status",
                                "id": 1,
                                "name": "New",
                                "position": 1,
                                "isDefault": true,
                                "isClosed": false,
                                "defaultDoneRatio": 0,
                                "createdAt": "2014-05-21T08:51:20Z",
                                "updatedAt": "2014-05-21T09:12:00Z"
                            },
                            {
                                "_links": { "self": { "href": "/api/v3/statuses/2" } },
                                "_type": "Status",
                                "id": 2,
                                "name": "Closed",
                                "position": 2,
                                "isDefault": false,
                                "isClosed": true,
                                "defaultDoneRatio": 100,
                                "createdAt": "2014-05-21T08:51:20Z",
                                "updatedAt": "2014-05-21T09:12:00Z"
                            }
                        ]
                    }
                }
            }

## view the schema [GET]

This is an example of how a schema might look like. Note that this endpoint does not exist in the actual implementation.

+ Response 200 (application/hal+json)

    [Example Schema][]

# Group Statuses

## Linked Properties
|  Link         | Description               | Type          | Constraints | Supported operations |
|:-------------:|-------------------------- | ------------- | ----------- | -------------------- |
| self          | This status               | Status        | not null    | READ                 |

## Local Properties
| Property         | Description                                                   | Type    | Constraints   | Supported operations |
| :--------:       | -------------                                                 | ------- | -----------   | -------------------- |
| id               | Status id                                                     | Integer | x > 0         | READ                 |
| name             | Status name                                                   | String  |               | READ                 |
| position         | Sort index of the status                                      | Integer |               | READ                 |
| isDefault        |                                                               | Boolean |               | READ                 |
| isClosed         | are tickets of this status considered closed?                 | Boolean |               | READ                 |
| defaultDoneRatio | The percentageDone being applied when changing to this status | Integer | 0 <= x <= 100 | READ                 |

## Statuses [/api/v3/statuses]

+ Model
    + Body

            {
                "_links":
                {
                    "self":
                    {
                        "href": "/api/v3/statuses"
                    }
                },
                "total": 6,
                "count": 6,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/1"
                                }
                            },
                            "_type": "Status",
                            "id": 1,
                            "name": "New",
                            "position": 1,
                            "isDefault": true,
                            "isClosed": false,
                            "defaultDoneRatio": 0
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/3"
                                }
                            },
                            "_type": "Status",
                            "id": 3,
                            "name": "Resolved",
                            "position": 3,
                            "isDefault": false,
                            "isClosed": false,
                            "defaultDoneRatio": 75
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/4"
                                }
                            },
                            "_type": "Status",
                            "id": 4,
                            "name": "Feedback",
                            "position": 4,
                            "isDefault": false,
                            "isClosed": false,
                            "defaultDoneRatio": 25
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/5"
                                }
                            },
                            "_type": "Status",
                            "id": 5,
                            "name": "Closed",
                            "position": 5,
                            "isDefault": false,
                            "isClosed": true,
                            "defaultDoneRatio": 100
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/6"
                                }
                            },
                            "_type": "Status",
                            "id": 6,
                            "name": "Rejected",
                            "position": 6,
                            "isDefault": false,
                            "isClosed": true,
                            "defaultDoneRatio": 100
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/statuses/2"
                                }
                            },
                            "_type": "Status",
                            "id": 2,
                            "name": "In Progress",
                            "position": 3,
                            "isDefault": false,
                            "isClosed": false,
                            "defaultDoneRatio": 50
                        }
                    ]
                }
            }

## List all Statuses [GET]

+ Response 200 (application/hal+json)

    [Statuses][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the statuses."
            }

## Status [/api/v3/statuses/{id}]

+ Model
    + Body

            {
                "_links":
                {
                    "self":
                    {
                        "href": "/api/v3/statuses/1"
                    }
                },
                "_type": "Status",
                "id": 1,
                "name": "New",
                "position": 1,
                "isDefault": true,
                "isClosed": false,
                "defaultDoneRatio": 0
            }

## View Status [GET]

+ Parameters
    + id (required, integer, `1`) ... status id

+ Response 200 (application/hal+json)

    [Status][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see this status."
            }

# Group String Objects

## Linked Properties
|  Link         | Description               | Type          | Constraints | Supported operations |
|:-------------:|-------------------------- | ------------- | ----------- | -------------------- |
| self          | This string object        | StringObject  | not null    | READ                 |

## Local Properties
| Property         | Description                                    | Type     | Constraints | Supported operations |
|:----------------:| ---------------------------------------------- | -------- | ----------- | -------------------- |
| value            | The value of the string                        | String   |             | READ                 |

String objects are a linkable representation of strings. They merely serve the purpose of making links to strings possible,
e.g. to be able to provide `allowedValues` for a string typed property.

## String Object [/api/v3/string_objects?value={value}]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/string_objects?value=Foo" }
                },
                "_type": "StringObject",
                "value": "Foo"
            }

## View String Object [GET]

+ Parameters
    + value (required, string, `Foo`) ... The string value being resolved

+ Response 200 (application/hal+json)

    [String Object][]

# Group Types

## Linked Properties
|  Link         | Description               | Type          | Constraints | Supported operations |
|:-------------:|-------------------------- | ------------- | ----------- | -------------------- |
| self          | This type                 | Type          | not null    | READ                 |

## Local Properties
| Property         | Description                                    | Type     | Constraints | Supported operations |
|:----------------:| ---------------------------------------------- | -------- | ----------- | -------------------- |
| id               | Type id                                        | Integer  | x > 0       | READ                 |
| name             | Type name                                      | String   |             | READ                 |
| color            | The color used to represent this type          | Color    |             | READ                 |
| position         | Sort index of the type                         | Integer  |             | READ                 |
| isDefault        |                                                | Boolean  |             | READ                 |
| isMilestone      | Do tickets of this type represent a milestone? | Boolean  |             | READ                 |
| createdAt        | Time of creation                               | DateTime |             | READ                 |
| updatedAt        | Time of the most recent change to the user     | DateTime |             | READ                 |

## Types [/api/v3/types]

+ Model
    + Body

            {
                "_links":
                {
                    "self":
                    {
                        "href": "/api/v3/types"
                    }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/types/1"
                                }
                            },
                            "_type": "Type",
                            "id": 1,
                            "name": "Bug",
                            "color": "#ff0000",
                            "position": 1,
                            "isDefault": true,
                            "isMilestone": false,
                            "createdAt": "2014-05-21T08:51:20Z",
                            "updatedAt": "2014-05-21T08:51:20Z"
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/types/2"
                                }
                            },
                            "_type": "Type",
                            "id": 2,
                            "name": "Feature",
                            "color": "#888",
                            "position": 2,
                            "isDefault": false,
                            "isMilestone": false,
                            "createdAt": "2014-05-21T08:51:20Z",
                            "updatedAt": "2014-05-21T08:51:20Z"
                        }
                    ]
                }
            }

## List all Types [GET]

+ Response 200 (application/hal+json)

    [Types][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package or manage types (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the types."
            }

## Types by Project [/api/v3/projects/{project_id}/types]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/11/types" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/types/1"
                                }
                            },
                            "_type": "Type",
                            "id": 1,
                            "name": "Bug",
                            "color": "#ff0000",
                            "position": 1,
                            "isDefault": true,
                            "isMilestone": false,
                            "createdAt": "2014-05-21T08:51:20Z",
                            "updatedAt": "2014-05-21T08:51:20Z"
                        },
                        {
                            "_links":
                            {
                                "self":
                                {
                                    "href": "/api/v3/types/2"
                                }
                            },
                            "_type": "Type",
                            "id": 2,
                            "name": "Feature",
                            "color": "#888",
                            "position": 2,
                            "isDefault": false,
                            "isMilestone": false,
                            "createdAt": "2014-05-21T08:51:20Z",
                            "updatedAt": "2014-05-21T08:51:20Z"
                        }
                    ]
                }
            }

## List types available in a project [GET]

This endpoint lists the types that are *available* in a given project.

+ Parameters
    + project_id (required, integer, `1`) ... ID of the project whoose types will be listed

+ Response 200 (application/hal+json)

    [Types by Project][]

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work packages **or** manage types (on given project)

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Type [/api/v3/types/{id}]

+ Model
    + Body

            {
                "_links":
                {
                    "self":
                    {
                        "href": "/api/v3/types/1"
                    }
                },
                "_type": "Type",
                "id": 1,
                "name": "Bug",
                "color": "#ff0000",
                "position": 1,
                "isDefault": true,
                "isMilestone": false,
                "createdAt": "2014-05-21T08:51:20Z",
                "updatedAt": "2014-05-21T08:51:20Z"
            }

## View Type [GET]

+ Parameters
    + id (required, integer, `1`) ... type id

+ Response 200 (application/hal+json)

    [Type][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package or manage types (on any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see this type."
            }

# Group Users

## Actions
| Link                | Description                                                          | Condition                                  |
|:-------------------:| -------------------------------------------------------------------- | ------------------------------------------ |
| lock                | Restrict the user from logging in and performing any actions         | not locked; **Permission**: Administrator  |
| showUser            | Link to the OpenProject user page (HTML)                             |                                            |
| unlock              | Allow a locked user to login and act again                           | locked; **Permission**: Administrator      |
| delete              | Permanently remove a user from the instance                          | **Permission**: Administrator, self-delete |

## Linked Properties
|  Link     | Description                                 | Type          | Constraints           | Supported operations |
|:---------:|-------------------------------------------- | ------------- | --------------------- | -------------------- |
| self      | This user                                   | User          | not null              | READ                 |

## Local Properties
| Property    | Description                                               | Type     | Constraints | Supported operations | Condition                 |
| :---------: | -------------                                             | ----     | ----------- | -------------------- | ------------------------- |
| id          | User's id                                                 | Integer  | x > 0       | READ                 |                           |
| login       | User's login name                                         | String   |             | READ                 |                           |
| firstName   | User's first name                                         | String   |             | READ                 |                           |
| lastName    | User's last name                                          | String   |             | READ                 |                           |
| name        | User's full name, formatting depends on instance settings | String   |             | READ                 |                           |
| email       | User's E-Mail address                                     | String   |             | READ                 | E-Mail address not hidden |
| avatar      | URL to user's avatar                                      | String   |             | READ                 |                           |
| status      | The current activation status of the user (see below)     | String   |             | READ                 |                           |
| createdAt   | Time of creation                                          | DateTime |             | READ                 |                           |
| updatedAt   | Time of the most recent change to the user                | DateTime |             | READ                 |                           |

The `status` of a user can be one of:

* `active` - the user can log in with the account
* `registered` - the user just registered to the instance, he can't log in yet, but will be able to, once the registration is completed
* `locked` - the user is locked and can't log in

## User [/api/v3/users/{id}]

+ Model
    + Body

            {
                "_type": "User",
                "_links": {
                    "self": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard - j.sheppard"
                    },
                    "showUser": {
                        "href": "/users/1",
                        "type": 'text/html'
                    },
                    "lock": {
                        "href": "/api/v3/users/1/lock",
                        "title": "Set lock on j.sheppard"
                        "method": "POST"
                    },
                    "delete": {
                        "href": "/api/v3/users/1",
                        "title": "Delete j.sheppard"
                        "method": "DELETE"
                    }
                },
                "id": 1,
                "login": "j.sheppard",
                "firstName": "John",
                "lastName": "Sheppard",
                "email": "shep@mail.com",
                "avatar": "https://gravatar/avatar",
                "status": "active",
                "createdAt": "2014-05-21T08:51:20Z",
                "updatedAt": "2014-05-21T08:51:20Z"
            }

## View user [GET]

+ Parameters
    + id (required, integer, `1`) ... User id

+ Response 200 (application/hal+json)

    [User][]

+ Response 404 (application/hal+json)

    Returned if the user does not exist.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified user does not exist."
            }

## Delete user [DELETE]

Permanently deletes the specified user account.

+ Parameters
    + id (required, integer, `1`) ... User id

+ Response 202

    Returned if the account was deleted successfully.

    Note that the response body is empty as of now. In future versions of the API a body
    *might* be returned, indicating the progress of deletion.

    + Body

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions or if deletion of users was disabled in the instance wide settings.

    **Required permission:** Administrators only (exception: users might be able to delete their own accounts)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to delete the account of this user."
            }

+ Response 404 (application/hal+json)

    Returned if the user does not exist.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified user does not exist."
            }


## User Account Locking [/api/v3/users/{id}/lock]

## Set Lock [POST]

+ Parameters
    + id (required, integer, `1`) ... User id

+ Response 200 (application/hal+json)

    [User][]

+ Response 400 (application/hal+json)

    Returned if the client tries to lock a user account whose current status does not allow this transition.

    **Required permission:** Administrators only

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidUserStatusTransition",
                "message": "The current user account status does not allow this operation."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions for locking a user.

    **Required permission:** Administrators only

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to lock the account of this user."
            }

+ Response 404 (application/hal+json)

    Returned if the user does not exist.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified user does not exist."
            }

## Remove Lock [DELETE]

+ Parameters
    + id (required, integer, `1`) ... User id

+ Response 200 (application/hal+json)

    [User][]

+ Response 400 (application/hal+json)

    Returned if the client tries to unlock a user account whose current status does not allow this transition.

    **Required permission:** Administrators only

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidUserStatusTransition",
                "message": "The current user account status does not allow this operation."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions for unlocking a user.

    **Required permission:** Administrators only

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to unlock the account of this user."
            }

+ Response 404 (application/hal+json)

    Returned if the user does not exist.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified user does not exist."
            }

# Group UserPreferences

## Linked Properties
|  Link     | Description                                              | Type           | Constraints           | Supported operations |
|:---------:|----------------------------------------------------------| -------------- | --------------------- | -------------------- |
| self      | This UserPreferences                                     | UserPreferences| not null              | READ                 |
| user      | The user that this preference belongs to                 | User           | not null              | READ                 |

## Local Properties
| Property               | Description                                                | Type       | Constraints | Supported operations |
|:----------------------:| -----------------------------------------------------------| ---------- | ----------- | -------------------- |
| hideMail               | Hide mail address from other users                         | Boolean    |             | READ / WRITE         |
| timeZone               | Current selected time zone                                 | String     |             | READ / WRITE         |
| theme                  | Current selected theme                                     | String     |             | READ / WRITE         |
| commentSortDescending  | Sort comments in descending order                          | Boolean    |             | READ / WRITE         |
| warnOnLeavingUnsaved   | Issue warning when leaving a page with unsaved text        | Boolean    |             | READ / WRITE         |
| accessibilityMode      | Enable accessibility mode                                  | Boolean    |             | READ / WRITE         |

## UserPreferences [/api/v3/my_preferences]

+ Model
    + Body

            {
                "_type" : "UserPreferences",
                "_links" : {
                    "self" : {
                        "href" : "/api/v3/my_preferences",
                    },
                    "user": {
                        "href": "/api/v3/users/1",
                        "title": "John Sheppard"
                    }
                },
                "hideMail" : false,
                "timeZone" : "Europe/Berlin",
                "theme" : "OpenProject",
                "commentSortDescending" : true,
                "warnOnLeavingUnsaved" : true,
                "accessibilityMode" : false
            }


## Show my preferences [GET]

+ Response 200 (application/hal+json)

    [UserPreferences][]

+ Response 401 (application/hal+json)

    Returned if no user is currently authenticated

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:Unauthenticated",
                "message": "You need to be authenticated to access this resource."
            }

## Update UserPreferences [PATCH]

When calling this endpoint the client provides a single object, containing the properties that it wants to change, in the body.

+ Request (application/json)

        {
            "accessibilityMode": true,
            "timeZone": "Europe/Paris"
        }

+ Response 200 (application/hal+json)

    [UserPreferences][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 401 (application/hal+json)

    Returned if no user is currently authenticated

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:Unauthenticated",
                "message": "You need to be authenticated to access this resource."
            }

+ Response 422 (application/hal+json)

    Returned if the update contains invalid properties.
    Reasons are:
    * Specifying an invalid type
    * Using an unknown time zone

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                "message": "Time zone is not set to one of the allowed values."
            }

# Group Versions

## Linked Properties
|  Link               | Description                              | Type          | Constraints                                                    | Supported operations |
|:-------------------:|----------------------------------------- | ------------- | -------------------------------------------------------------- | -------------------- |
| self                | This version                             | Version       | not null                                                       | READ                 |
| definingProject     | The project to which the version belongs | Project       | only present if the project is visible for the current user    | READ                 |
| availableInProjects | Projects where this version can be used  | Projects      | not null                                                       | READ                 |

## Local Properties
| Property    | Description                                   | Type        | Constraints | Supported operations |
| :---------: | --------------------------------------------- | ----------- | ----------- | -------------------- |
| id          | Version id                                    | Integer     | x > 0       | READ                 |
| name        | Version name                                  | String      | not null    | READ                 |
| description |                                               | Formattable | not null    | READ                 |
| startDate   |                                               | Date        |             | READ                 |
| endDate     |                                               | Date        |             | READ                 |
| status      | The current status of the version             | String      | not null    | READ                 |
| createdAt   | Time of creation                              | DateTime    | not null    | READ                 |
| updatedAt   | Time of the most recent change to the version | DateTime    | not null    | READ                 |

## Versions by Project [/api/v3/projects/{project_id}/versions]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/11/versions" }
                },
                "total": 3,
                "count": 3,
                "_type": "Collection",
                "_embedded":
                {
                    "elements": [
                        {
                            "_links": {
                                "self": { "href": "/api/v3/versions/11" },
                                "definingProject": { "href": "/api/v3/projects/11" },
                                "availableInProjects": { "href": "/api/v3/versions/11/projects" }
                            },
                            "_type": "Version",
                            "id": 11,
                            "name": "v3.0 Alpha",
                            "description": {
                                "format": "plain",
                                "raw": "This version has a description",
                                "html": "This version has a description"
                            },
                            "startDate": "2014-11-20",
                            "endDate": null,
                            "status": "Open"
                        },
                        {
                            "_links": {
                                "self": { "href": "/api/v3/versions/12" },
                                "definingProject": { "href": "/api/v3/projects/11" },
                                "availableInProjects": { "href": "/api/v3/versions/12/projects" }
                            },
                            "_type": "Version",
                            "id": 12,
                            "name": "v2.0",
                            "description": {
                                "format": "plain",
                                "raw": "",
                                "html": ""
                            },
                            "startDate": null,
                            "endDate": null,
                            "status": "Closed"
                        },
                        {
                            "_links": {
                                "self": { "href": "/api/v3/versions/10" },
                                "definingProject": { "href": "/api/v3/projects/11" },
                                "availableInProjects": { "href": "/api/v3/versions/10/projects" }
                            },
                            "_type": "Version",
                            "id": 10,
                            "name": "v1.0",
                            "description": {
                                "format": "plain",
                                "raw": "",
                                "html": ""
                            },
                            "startDate": null,
                            "endDate": null,
                            "status": "Open"
                        }
                    ]
                }
            }

## List versions available in a project [GET]

This endpoint lists the versions that are *available* in a given project.
Note that due to sharing this might be more than the versions *defined* by that project.

+ Parameters
    + project_id (required, integer, `1`) ... ID of the project whoose versions will be listed

+ Response 200 (application/hal+json)

    [Versions by Project][]

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work packages **or** manage versions (on given project)

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Version [/api/v3/versions/{id}]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/versions/11" },
                    "definingProject": { "href": "/api/v3/projects/11" },
                    "availableInProjects": { "href": "/api/v3/versions/11/projects" }
                },
                "_type": "Version",
                "id": 11,
                "name": "v3.0 Alpha",
                "description": {
                    "format": "plain",
                    "raw": "This version has a description",
                    "html": "This version has a description"
                },
                "startDate": "2014-11-20",
                "endDate": null,
                "status": "Open"
            }

## View Version [GET]

+ Parameters
    + id (required, integer, `1`) ... version id

+ Response 200 (application/hal+json)

    [Version][]

+ Response 404 (application/hal+json)

    Returned if the version does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work packages **or** manage versions (any project where the version is available)

    *Note: A client without sufficient permissions shall not be able to test for the existence of
    a version. That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified version does not exist."
            }

# Group Work Packages

## Actions

| Link                | Description                                                          | Condition                         |
|:-------------------:|----------------------------------------------------------------------| --------------------------------- |
| update              | Form endpoint that aids in preparing and performing edits on a WP    | **Permission**: edit work package |
| updateImmediately   | Directly perform edits on a work package                             | **Permission**: edit work package |
| watch               | Add current user to WP watchers                                      | logged in; not watching           |
| unwatch             | Remove current user from WP watchers                                 | logged in; watching               |
| addWatcher          | Add any user to WP watchers                                          | **Permission**: add watcher       |
| removeWatcher       | Remove any user from WP watchers                                     | **Permission**: delete watcher    |
| addAttachment       | Attach a file to the WP                                              | **Permission**: edit work package |

## Linked Properties

| Link               | Description                                                                                                                                           | Type         | Constraints  | Supported operations  | Condition                                 |
| :----------------: | ----------------------------------------------------------------------------------------------------------------------------------------------------- | ------------ | ------------ | --------------------- | ----------------------------------------- |
| self               | This work package                                                                                                                                     | WorkPackage  | not null     | READ                  |                                           |
| schema             | The schema of this work package                                                                                                                       | Schema       | not null     | READ                  |                                           |
| attachments        | The files attached to this work package                                                                                                               | Collection   | not null     | READ                  |                                           |
| author             | The person that created the work package                                                                                                              | User         | not null     | READ                  |                                           |
| assignee           | The person that is intended to work on the work package                                                                                               | User         |              | READ / WRITE          |                                           |
| availableWatchers  | All users that can be added to the work package as watchers.                                                                                          | User         |              | READ                  | **Permission** add work package watchers  |
| category           | The category of the work package                                                                                                                      | Category     |              | READ / WRITE          |                                           |
| priority           | The priority of the work package                                                                                                                      | Priority     | not null     | READ / WRITE          |                                           |
| project            | The project to which the work package belongs                                                                                                         | Project      | not null     | READ / WRITE          |                                           |
| responsible        | The person that is responsible for the overall outcome                                                                                                | User         |              | READ / WRITE          |                                           |
| revisions          | Revisions that are referencing the work package                                                                                                       | Revision     |              | READ                  | **Permission** view changesets            |
| status             | The current status of the work package                                                                                                                | Status       | not null     | READ / WRITE          |                                           |
| timeEntries        | All time entries logged on the work package. Please note that this is a link to an HTML resource for now and as such, the link is subject to change.  | N/A          |              | READ                  | **Permission** view time entries          |
| type               | The type of the work package                                                                                                                          | Type         | not null     | READ / WRITE          |                                           |
| version            | The version associated to the work package                                                                                                            | Version      |              | READ / WRITE          |                                           |
| watchers           | All users that are currently watching this work package                                                                                               | Collection   |              | READ                  | **Permission** view work package watchers |

## Local Properties

| Property         | Description                                            | Type        | Constraints                                                                                                                                                  | Supported operations | Condition                        |
| :--------------: | ------------------------------------------------------ | ----------- | ------------------------------------------------------------------------------------------------------                                                       | -------------------- | -------------------------------- |
| id               | Work package id                                        | Integer     | x > 0                                                                                                                                                        | READ                 |                                  |
| lockVersion      | The version of the item as used for optimistic locking | Integer     |                                                                                                                                                              | READ                 |                                  |
| subject          | Work package subject                                   | String      | not null; 1 <= length <= 255                                                                                                                                 | READ / WRITE         |                                  |
| type             | Name of the work package's type                        | String      | not null                                                                                                                                                     | READ                 |                                  |
| description      | The work package description                           | Formattable |                                                                                                                                                              | READ / WRITE         |                                  |
| parentId         | Parent work package id                                 | Integer     | Must be an id of an existing and visible (for the current user) work package                                                                                 | READ / WRITE         |                                  |
| startDate        | Scheduled beginning of a work package                  | Date        | Cannot be set for parent work packages; must be equal or greater than the earliest possible start date; Exists only on work packages of a non milestone type | READ / WRITE         |                                  |
| dueDate          | Scheduled end of a work package                        | Date        | Cannot be set for parent work packages; must be greater than or equal to the start date; Exists only on work packages of a non milestone type                | READ / WRITE         |                                  |
| date             | Date on which a milestone is achieved                  | Date        | Exists only on work packages of a milestone type
| estimatedTime    | Time a work package likely needs to be completed       | Duration    | Cannot be set for parent work packages                                                                                                                       | READ / WRITE         |                                  |
| spentTime        |                                                        | Duration    |                                                                                                                                                              | READ                 | **Permission** view time entries |
| percentageDone   | Amount of total completion for a work package          | Integer     | 0 <= x <= 100; Cannot be set for parent work packages                                                                                                        | READ / WRITE         |                                  |
| createdAt        | Time of creation                                       | DateTime    |                                                                                                                                                              | READ                 |                                  |
| updatedAt        | Time of the most recent change to the work package     | DateTime    |                                                                                                                                                              | READ                 |                                  |

*Note that the properties listed here only cover the built-in properties of the OpenProject Core.
Using plug-ins and custom fields a work package might contain various additional properties.
A client can consult the schema information to which the work package links. The schema will contain information about
all properties of the linking work package, including properties added by plug-ins and custom fields.*

*Custom fields are identified by a key in the form of `customFieldN`, where `N` is an integer. Depending on their type,
they can occur as properties or as linked properties. A client has to consult the schema to resolve
the human readable name of custom fields.*

*Properties that cannot be set directly on parent work packages are inferred from their children instead:*

* `startDate` is the earliest start date from its children
* `dueDate` is the latest due date from its children
* `estimatedTime` is the sum of estimated times from its children
* `percentageDone` is the weighted average of the sum of its children percentages done. The weight is given by the average of its children estimatedHours. However, if the percentage done is given by a work package's status, then only the status matters and no value is inferred.

*Start date can also not be earlier than a due date of any predecessor.*

## Work Package [/api/v3/work_packages/{id}{?notify}]

+ Model
    + Body

            {
                "_type": "WorkPackage",
                "_links": {
                    "self": {
                        "href": "/api/v3/work_packages/1528",
                        "title": "Develop API"
                    },
                    "schema": { "href": "/api/v3/work_packages/schemas/1-1-2" },
                    "update": {
                        "href": "/api/v3/work_packages/1528",
                        "method": "patch",
                        "title": "Update Develop API"
                    },
                    "delete": {
                        "href": "/work_packages/bulk?ids=1528",
                        "method": "delete",
                        "title": "Delete Develop API"
                    },
                    "log_time": {
                        "href": "/work_packages/1528/time_entries/new",
                        "type": "text/html",
                        "title": "Log time on Develop API"
                    },
                    "move": {
                        "href": "/work_packages/1528/move/new",
                        "type": "text/html",
                        "title": "Move Develop API"
                    },
                    "attachments": {
                        "href": "/api/v3/work_packages/1528/attachments"
                    },
                    "addAttachment": {
                        "href": "/api/v3/work_packages/1528/attachments",
                        "method": "post"
                    },
                    "author": {
                        "href": "/api/v3/users/1",
                        "title": "OpenProject Admin - admin"
                    },
                    "responsible": {
                        "href": "/api/v3/users/23",
                        "title": "Laron Leuschke - Alaina5788"
                    },
                    "revisions": {
                        "href": "/api/v3/work_packages/1528/revisions"
                    },
                    "assignee": {
                        "href": "/api/v3/users/11",
                        "title": "Emmie Okuneva - Adele5450"
                    },
                    "priority": {
                        "href": "/api/v3/priorities/2",
                        "title": "Normal"
                    },
                    "project": {
                        "href": "/api/v3/projects/1",
                        "title": "A Test Project"
                    },
                    "status": {
                        "href": "/api/v3/statuses/1",
                        "title": "New"
                    },
                    "type": {
                        "href": "/api/v3/types/1",
                        "title": "New"
                    },
                    "version": {
                        "href": "/api/v3/versions/1",
                        "title": "Version 1"
                    },
                    "availableWatchers": {
                        "href": "/api/v3/work_packages/1528/available_watchers"
                    },
                    "watch": {
                        "href": "/api/v3/work_packages/1528/watchers",
                        "method": "post",
                        "payload": {
                            "user": { "href": "/api/v3/users/1" }
                        }
                    },
                    "addWatcher": {
                        "href": "/api/v3/work_packages/1528/watchers",
                        "method": "post",
                        "payload": {
                            "user": { "href": "/api/v3/users/{user_id}" }
                        },
                        "templated": true
                    },
                    "removeWatcher": {
                        "href": "/api/v3/work_packages/1528/watchers/{user_id}",
                        "method": "delete",
                        "templated": true
                    },
                    "addRelation": {
                        "href": "/api/v3/work_packages/1528/relations",
                        "method": "post",
                        "title": "Add relation"
                    },
                    "changeParent": {
                      "href": "/api/v3/work_packages/694",
                      "method": "patch",
                      "title": "Change parent of Bug in OpenProject"
                    },
                    "addComment": {
                        "href": "/api/v3/work_packages/1528/activities",
                        "method": "post",
                        "title": "Add comment"
                    },
                    "parent": {
                        "href": "/api/v3/work_packages/1298",
                        "title": "nisi eligendi officiis eos delectus quis voluptas dolores"
                    },
                    "category": {
                        "href": "/api/v3/categories/1298",
                        "title": "eligend isi"
                    },
                    "children": [
                        {
                            "href": "/api/v3/work_packages/1529",
                            "title": "Write API documentation"
                        }
                    ],
                    "timeEntries": {
                        "href": "/work_packages/1528/time_entries",
                        "type": "text/html",
                        "title": "Time entries"
                    },
                    "watchers": {
                        "href": "/api/v3/work_packages/1528/watchers"
                    },
                    "customField3": {
                        "href": "api/v3/users/14"
                    }
                },
                "id": 1528,
                "subject": "Develop API",
                "description": {
                    "format": "textile",
                    "raw": "Develop super cool OpenProject API.",
                    "html": "<p>Develop super cool OpenProject API.</p>"
                },
                "startDate": null,
                "dueDate": null,
                "estimatedTime": "PT2H",
                "percentageDone": 0,
                "parentId": 1298,
                "customField1": "Foo",
                "customField2": 42,
                "createdAt": "2014-08-29T12:40:53Z",
                "updatedAt": "2014-08-29T12:44:41Z"
            }

## View Work Package [GET]

+ Parameters
    + id (required, integer, `1`) ... Work package id

+ Response 200 (application/hal+json)

    [Work Package][]

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Edit Work Package [PATCH]

When calling this endpoint the client provides a single object, containing the properties and links that it wants to change, in the body.
Note that it is only allowed to provide properties or links supporting the **write** operation.

Additionally to the fields the client wants to change, it is mandatory to provide the value of `lockVersion` which was received
by the `GET` request this change originates from.

The value of `lockVersion` is used to implement [optimistic locking](http://en.wikipedia.org/wiki/Optimistic_concurrency_control).

+ Parameters
    + id (required, integer, `1`) ... Work package id

    + notify = `true` (optional, boolean, `false`) ... Indicates whether change notifications (e.g. via E-Mail) should be sent.
    Note that this controls notifications for all users interested in changes to the work package (e.g. watchers, author and assignee),
    not just the current user.

+ Request (application/json)

        {
            "lockVersion": 13,
            "subject": "Lorem"
            "parentId": "42"
        }

+ Response 200 (application/hal+json)

    [Work Package][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to edit the content of the work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

+ Response 409 (application/hal+json)

    Returned if the resource was changed since the client requested it. This is determined using the `lockVersion` property.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:UpdateConflict",
                "message": "Your changes could not be saved, because the work package was changed since you've seen it the last time."
            }

+ Response 422 (application/hal+json)

    Returned if:

    * the client tries to modify a read-only property (`PropertyIsReadOnly`)
    * a constraint for a property was violated (`PropertyConstraintViolation`)
    * the client provides a link to an invalid resource (`ResourceTypeMismatch`)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                "message": "The subject might not be blank.",
                "_embedded": {
                    "details": {
                        "attribute": "Subject"
                    }
                }
            }

## Delete Work Package [DELETE]

Deletes the work package, as well as:

* all associated time entries
* its hierarchy of child work packages

+ Parameters
    + id (required, integer, `1`) ... Work package id

+ Response 204 (application/hal+json)

    Returned if the work package was deleted successfully.

    Note that the response body is empty as of now. In future versions of the API a body
    *might* be returned along with an appropriate HTTP status.

    + Body

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** delete work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to delete this work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Work Package Schema [/api/v3/work_packages/schemas/{identifier}]

## View Work Package Schema [GET]

+ Parameters
    + identifier (required, string, `12-13`) ... Identifier of the schema

+ Response 200 (application/hal+json)

    [Example Schema][]

+ Response 404 (application/hal+json)

    Returned if the schema does not exist or the client does not have sufficient permissions
    to see it.

    **Required permission:** view work packages (on the project where this schema is used)

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified schema does not exist."
            }

## Work Package Edit Form [/api/v3/work_packages/{id}/form]

This endpoint returns a form to allow a guided modification of an existing work package.

For more details and all possible responses see the general specification of [Forms](#forms).

## Work Package Edit Form [POST]

+ Parameters
    + id (required, integer, `1`) ... ID of the work package being modified

+ Response 200 (application/hal+json)

    [Example Form][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit work package

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to edit the specified work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Work Packages [/api/v3/work_packages{?notify,offset,pageSize,filters,sortBy,groupBy,showSums}]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                    "elements": [
                    {
                        "_type": "WorkPackage",
                        "_links": {
                            "self": {
                                "href": "/api/v3/work_packages/1"
                            }
                        },
                        "id": 1,
                        "subject": "Skipped other properties for brevity"
                    },
                    {
                        "_type": "WorkPackage",
                        "_links": {
                            "self": {
                                "href": "/api/v3/work_packages/2"
                            }
                        },
                        "id": 2,
                        "subject": "Skipped other properties for brevity"
                    }]
                }
            }

## List Work Packages [GET]

+ Parameters
    + offset = `1` (optional, integer, `25`) ... Page number inside the requested collection.

    + pageSize (optional, integer, `25`) ... Number of elements to display per page.

    + filters (optional, string, `[{ "status_id": { "operator": "o", "values": null }" }]`) ... JSON specifying filter conditions.
    Accepts the same format as returned by the [queries](#queries) endpoint.

    + sortBy (optional, string, `[["status", "asc"]]`) ... JSON specifying sort criteria.
    Accepts the same format as returned by the [queries](#queries) endpoint.

    + groupBy (optional, string, `status`) ... The column to group by.

    + showSums = `false` (optional), boolean, `true` ... Indicates whether properties should be summed up if they support it.

+ Response 200 (application/hal+json)

    [Work Packages][]

+ Response 400 (application/hal+json)

    Returned if the client sends a query parameter, that the server knows, but does not understand.
    E.g. by providing a syntactically incorrect `filters` parameter.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidQuery",
                "message": "Operator can't be blank."
            }


+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work packages (globally or in any project)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see work packages."
            }

## Create Work Package [POST]

When calling this endpoint the client provides a single object, containing at least the properties and links that are required, in the body.
The required fields of a WorkPackage can be found in its schema, which is embedded in the respective form.
Note that it is only allowed to provide properties or links supporting the write operation.

A project link must be set when creating work packages through this route.

+ Parameters
    + notify = `true` (optional, boolean, `false`) ... Indicates whether change notifications (e.g. via E-Mail) should be sent.
    Note that this controls notifications for all users interested in changes to the work package (e.g. watchers, author and assignee),
    not just the current user.

+ Response 200 (application/hal+json)

    [Work Package][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** add work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to add work packages to this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permissions:** view project

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

+ Response 422 (application/hal+json)

    Returned if:
    * the client tries to write a read-only property
    * a constraint for a property was violated
    * a property was provided in an unreadable format

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                "message": "The subject might not be blank.",
                "_embedded": {
                    "details": {
                        "attribute": "Subject"
                    }
                }
            }

## Work Package Create Form [/api/v3/work_packages/form]

This endpoint returns a form to allow a guided creation of a new work package.
The returned form will be pre-filled with default values for every property, if available.

For more details and all possible responses see the general specification of [Forms](#forms).
A project link must be set when creating work packages through this route.

## Work Package Create Form [POST]

+ Response 200 (application/hal+json)

    [Example Form][]


## Work Packages by Project [/api/v3/projects/{id}/work_packages{?offset,pageSize,filters,sortBy,groupBy,showSums,notify}]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/14/work_packages" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                    "elements": [
                    {
                        "_type": "WorkPackage",
                        "_links": {
                            "self": {
                                "href": "/api/v3/work_packages/1"
                            }
                        },
                        "id": 1,
                        "subject": "Skipped other properties for brevity"
                    },
                    {
                        "_type": "WorkPackage",
                        "_links": {
                            "self": {
                                "href": "/api/v3/work_packages/2"
                            }
                        },
                        "id": 2,
                        "subject": "Skipped other properties for brevity"
                    }]
                }
            }

## List Work Packages [GET]

+ Parameters
    + id (required, integer, `1`) ... Project id

    + offset = `1` (optional, integer, `25`) ... Page number inside the requested collection.

    + pageSize (optional, integer, `25`) ... Number of elements to display per page.

    + filters (optional, string, `[{ "status_id": { "operator": "o", "values": null }" }]`) ... JSON specifying filter conditions.
    Accepts the same format as returned by the [queries](#queries) endpoint.

    + sortBy (optional, string, `[["status", "asc"]]`) ... JSON specifying sort criteria.
    Accepts the same format as returned by the [queries](#queries) endpoint.

    + groupBy (optional, string, `status`) ... The column to group by.

    + showSums = `false` (optional), boolean, `true` ... Indicates whether properties should be summed up if they support it.

+ Response 200 (application/hal+json)

    [Work Packages by Project][]

+ Response 400 (application/hal+json)

    Returned if the client sends a query parameter, that the server knows, but does not understand.
    E.g. by providing a syntactically incorrect `filters` parameter.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidQuery",
                "message": "Operator can't be blank."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the work packages of this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Create Work Package [POST]

When calling this endpoint the client provides a single object, containing at least the properties and links that are required, in the body.
The required fields of a WorkPackage can be found in its schema, which is embedded in the respective form.
Note that it is only allowed to provide properties or links supporting the write operation.

+ Parameters
    + id (required, integer, `1`) ... Project id

    + notify = `true` (optional, boolean, `false`) ... Indicates whether change notifications (e.g. via E-Mail) should be sent.
    Note that this controls notifications for all users interested in changes to the work package (e.g. watchers, author and assignee),
    not just the current user.

+ Response 200 (application/hal+json)

    [Work Package][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** add work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to add work packages to this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions
    to see it.

    **Required permissions:** view project

    *Note: A client without sufficient permissions shall not be able to test for the existence of a project.
    That's why a 404 is returned here, even if a 403 might be more appropriate.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

+ Response 422 (application/hal+json)

    Returned if:
    * the client tries to write a read-only property
    * a constraint for a property was violated
    * a property was provided in an unreadable format

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:PropertyConstraintViolation",
                "message": "The subject might not be blank.",
                "_embedded": {
                    "details": {
                        "attribute": "Subject"
                    }
                }
            }

## Work Package Create Form [/api/v3/projects/{id}/work_packages/form]

This endpoint returns a form to allow a guided creation of a new work package.
The returned form will be pre-filled with default values for every property, if available.

For more details and all possible responses see the general specification of [Forms](#forms).

## Work Package Create Form [POST]

+ Parameters
    + id (required, integer, `1`) ... ID of the project in which the work package will be created

+ Response 200 (application/hal+json)

    [Example Form][]

## Watchers [/api/v3/work_packages/{work_package_id}/watchers]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages/14/watchers" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/1",
                                "title": "John Sheppard - j.sheppard"
                            },
                            "showUser": {
                                "href": "/users/1",
                                "type": 'text/html'
                            },
                            "lock": {
                                "href": "/api/v3/users/1/lock",
                                "title": "Set lock on j.sheppard"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/1",
                                "title": "Delete j.sheppard"
                                "method": "DELETE"
                            }
                        },
                        "id": 1,
                        "login": "j.sheppard",
                        "firstName": "John",
                        "lastName": "Sheppard",
                        "mail": "shep@mail.com",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    },
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/2",
                                "title": "Jim Sheppard - j.sheppard2"
                            },
                            "lock": {
                                "href": "/api/v3/users/2/lock",
                                "title": "Set lock on j.sheppard2"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/2",
                                "title": "Delete j.sheppard2"
                                "method": "DELETE"
                            }
                        },
                        "id": 2,
                        "login": "j.sheppard2",
                        "firstName": "Jim",
                        "lastName": "Sheppard",
                        "mail": "shep@mail.net",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    }]
                }
            }

## List watchers [GET]

+ Parameters
    + work_package_id (required, integer, `1`) ... Work package id

+ Response 200 (application/hal+json)

    [Watchers][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work package watchers

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the watchers of this work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    *Note that you will effectively not be able to see the watchers of a work package without being able to see the work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Add watcher [POST]

Adds a watcher to the specified work package.

The request is expected to contain a single JSON object, that contains a link object under the `user` key.

The response will be user added as watcher.
In case the user was already watching the work package an `HTTP 200` is returned, an
`HTTP 201` if the user was added as a new watcher.

+ Parameters
    + work_package_id (required, integer, `1`) ... Work package id

+ Request (application/json)

        {
            "user": { "href": "/api/v3/users/1" }
        }

+ Response 200 (application/hal+json)

    [User][]

+ Response 201 (application/hal+json)

    [User][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    For example:

    * The request did not contain a single JSON object
    * The JSON object did not contain the key `user`
    * The value of `users` was not a link object

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permissions:**

    * view work package (for self)
    * add work package watchers (for other users)

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to add watchers to this work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    *Note that you will effectively not be able to change the watchers of a work package without being able to see the work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

+ Response 422 (application/hal+json)

    Returned if:

    * the client tries to specify a link to a resource that is not a user (`ResourceTypeMismatch`)
    * the user specified is not allowed to watch that work package (`PropertyConstraintViolation`)
    * the user specified does not exist (`PropertyConstraintViolation`)

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:ResourceTypeMismatch",
                "message": "Expected resource of type 'User', but got a 'Status'.",
            }

## Remove Watcher [/api/v3/work_packages/{work_package_id}/watchers/{id}]

## Remove watcher [DELETE]

Removes the specified user from the list of watchers for the given work package.

If the request succeeds, the specified user is not watching the work package anymore.

*Note: This might also be the case, if the specified user did not watch the work package prior to the request.*

+ Parameters
    + work_package_id (required, integer, `1`) ... Work package id
    + id (required, integer, `1`) ... User id

+ Response 204

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** delete work package watchers

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to remove watchers from this work package."
            }

+ Response 404 (application/hal+json)

    Returned in one of the following cases:

    Either the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    Or the specified user does not exist at all.

    *Note that you will effectively not be able to change the watchers of a work package without being able to see the work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Available Watchers [/api/v3/work_packages/{id}/available_watchers]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages/1/available_watchers" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/1",
                                "title": "John Sheppard - j.sheppard"
                            },
                            "lock": {
                                "href": "/api/v3/users/1/lock",
                                "title": "Set lock on j.sheppard"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/1",
                                "title": "Delete j.sheppard"
                                "method": "DELETE"
                            }
                        },
                        "id": 1,
                        "login": "j.sheppard",
                        "firstName": "John",
                        "lastName": "Sheppard",
                        "email": "shep@mail.com",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    },
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/2",
                                "title": "Jim Sheppard - j.sheppard2"
                            },
                            "lock": {
                                "href": "/api/v3/users/2/lock",
                                "title": "Set lock on j.sheppard2"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/2",
                                "title": "Delete j.sheppard2"
                                "method": "DELETE"
                            }
                        },
                        "id": 2,
                        "login": "j.sheppard2",
                        "firstName": "Jim",
                        "lastName": "Sheppard",
                        "email": "shep@mail.net",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    }]
                }
            }

## Available watchers [GET]

Gets a list of users that are able to be watchers of the specified work package.

+ Parameters
    + id (required, integer, `1`) ... work package id

+ Response 200 (application/hal+json)

    [Available Watchers][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** add work package watchers

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not authorized to access this resource."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Available Projects [/api/v3/work_packages/{id}/available_projects]

+ Model
    + Body

            {
              "_links": {
                "self": {
                  "href": "/api/v3/work_packages/5/available_projects"
                }
              },
              "_type": "Collection",
              "total": 2,
              "count": 2,
              "_embedded": {
                "elements": [
                  {
                    "_type": "Project",
                    "_links": {
                      "self": {
                        "href": "/api/v3/projects/6",
                        "title": "A project"
                      },
                      "createWorkPackage": {
                        "href": "/api/v3/projects/6/work_packages/form",
                        "method": "post"
                      },
                      "createWorkPackageImmediate": {
                        "href": "/api/v3/projects/6/work_packages",
                        "method": "post"
                      },
                      "categories": {
                        "href": "/api/v3/projects/6/categories"
                      },
                      "versions": {
                        "href": "/api/v3/projects/6/versions"
                      }
                    },
                    "id": 6,
                    "identifier": "a_project",
                    "name": "A project",
                    "description": "Eveniet molestias omnis quis aut qui eum adipisci. Atque aut aut in exercitationem adipisci amet. Nisi asperiores quia ratione veritatis enim exercitationem magnam. Aut fuga architecto adipisci nihil. Et repellat pariatur. Aliquam et sed perferendis nostrum quaerat. Fugit doloremque voluptatem.",
                    "createdAt": "2015-07-06T13:28:14+00:00",
                    "updatedAt": "2015-10-01T09:55:02+00:00",
                    "type": "Customer Project"
                  },
                  {
                    "_type": "Project",
                    "_links": {
                      "self": {
                        "href": "/api/v3/projects/14",
                        "title": "Another project"
                      },
                      "createWorkPackage": {
                        "href": "/api/v3/projects/14/work_packages/form",
                        "method": "post"
                      },
                      "createWorkPackageImmediate": {
                        "href": "/api/v3/projects/14/work_packages",
                        "method": "post"
                      },
                      "categories": {
                        "href": "/api/v3/projects/14/categories"
                      },
                      "versions": {
                        "href": "/api/v3/projects/14/versions"
                      }
                    },
                    "id": 14,
                    "identifier": "another_project",
                    "name": "Another project",
                    "description": "",
                    "createdAt": "2016-02-29T12:50:20+00:00",
                    "updatedAt": "2016-02-29T12:50:20+00:00",
                    "type": null
                  }]
                }
              }
            }

## Available projects [GET]

Gets a list of projects that are available as projects to which the work package can be moved.

+ Parameters
    + id (required, integer, `1`) ... work package id

+ Response 200 (application/hal+json)

    [Available Projects][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** edit work package

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not authorized to access this resource."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }





## Revisions [/api/v3/work_packages/{id}/revisions]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages/42/revisions" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "Revision",
                        "_links": {
                            "self": {
                                "href": "/api/v3/revisions/13",
                            },
                            "project": {
                                "href": "/api/v3/projects/1",
                                "title": "A Test Project
                            },
                            "author": {
                                "href": "/api/v3/users/1",
                                "title": "John Sheppard - j.sheppard"
                            },
                            "showRevision": {
                                "href": "/projects/identifier/repository/revision/11f4b07"
                            }
                        },
                        "id": 13,
                        "identifier": "11f4b07dff4f4ce9548a52b7d002daca7cd63ec6",
                        "formattedIdentifier": "11f4b07",
                        "authorName": "John Sheppard",
                        "message": {
                            "format": "plain",
                            "raw": "This revision provides new features\n\nAn elaborate description",
                            "html": "<p>This revision provides new features<br/><br/>An elaborate description</p>"
                        },
                        "createdAt": "2015-07-21T13:36:59Z",
                    },
                    {
                        "_type": "Revision",
                        "_links": {
                            "self": {
                                "href": "/api/v3/revisions/14",
                            },
                            "project": {
                                "href": "/api/v3/projects/1",
                                "title": "A Test Project
                            },
                            "author": {
                                "href": "/api/v3/users/2",
                                "title": "Jim Sheppard - j.sheppard"
                            }
                            "showRevision": {
                                "href": "/projects/identifier/repository/revision/029ed72a"
                            }
                        },
                        "id": 13,
                        "identifier": "029ed72a3b7b7c4ab332b1f6eaa6576e7c946059",
                        "formattedIdentifier": "029ed72a",
                        "authorName": "j1msheppard",
                        "message": {
                            "format": "plain",
                            "raw": "This revision fixes some stuff\n\nMore information here",
                            "html": "<p>This revision fixes some stuff<br/><br/>More information here</p>"
                        },
                        "createdAt": "2015-06-30T08:47:00Z",
                    }]
                }
            }


## Revisions [GET]

Gets a list of revisions that are linked to this work package, e.g., because it is referenced in the commit message of the revision.

+ Parameters
    + id (required, integer, `1`) ... work package id

+ Response 200 (application/hal+json)

    [Revisions][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view changesets of the project this work package is contained in

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see linked revisions for this work package."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work project does not exist."
            }


## Work Package activities [/api/v3/work_packages/{id}/activities{?notify}]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/work_packages/1/revisions" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "Activity",
                        "_links": {
                            "self": {
                                "href": "/api/v3/activity/1"
                            },
                            "workPackage": {
                                "href": "/api/v3/work_packages/1"
                            },
                            "user": {
                                "href": "/api/v3/users/1"
                            }
                        },
                        "id": 1,
                        "details": [ ],
                        "comment": {
                            "format": "textile",
                            "raw": "Lorem ipsum dolor sit amet.",
                            "html": "<p>Lorem ipsum dolor sit amet.</p>"
                        },
                        "createdAt": "2014-05-21T08:51:20Z",
                        "version": 1
                    },
                    {
                        "_type": "Activity",
                        "_links": {
                            "self": {
                                "href": "/api/v3/activity/2"
                            },
                            "workPackage": {
                                "href": "/api/v3/work_packages/1"
                            },
                            "user": {
                                "href": "/api/v3/users/1"
                            }
                        },
                        "id": 2,
                        "details": [ ],
                        "comment": {
                            "format": "textile",
                            "raw": "Lorem ipsum dolor sit amet.",
                            "html": "<p>Lorem ipsum dolor sit amet.</p>"
                        },
                        "createdAt": "2014-05-21T08:51:22Z",
                        "version": 2
                    }]
                }
            }

## List work package activities [GET]

+ Parameters
    + id (required, integer, `1`) ... Work package id

+ Response 200 (application/hal+json)

    [Activity][]

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Comment work package [POST]

Creates an activity for the selected work package and, on success, returns the
updated activity.

+ Parameters
    + id (required, integer, `1`) ... Work package id

    + notify = `true` (optional, boolean, `false`) ... Indicates whether change notifications (e.g. via E-Mail) should be sent.
    Note that this controls notifications for all users interested in changes to the work package (e.g. watchers, author and assignee),
    not just the current user.

+ Request (application/json)

        {
          "comment": { "raw": "I think this is awesome!" }
        }

+ Response 201 (application/hal+json)

    [Activity][]

+ Response 400 (application/hal+json)

    Occurs when the client did not send a valid JSON object in the request body.

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:InvalidRequestBody",
                "message": "The request body was not a single JSON object."
            }

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** create journals

    *Note that you will only receive this error, if you are at least allowed to see the corresponding work package.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to create a comment here."
            }

+ Response 404 (application/hal+json)

    Returned if the work package does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view work package

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified work package does not exist."
            }

## Available Assignees [/api/v3/projects/{project_id}/work_packages/available_assignees]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/42/work_packages/available_assignees" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/1",
                                "title": "John Sheppard - j.sheppard"
                            },
                            "lock": {
                                "href": "/api/v3/users/1/lock",
                                "title": "Set lock on j.sheppard"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/1",
                                "title": "Delete j.sheppard"
                                "method": "DELETE"
                            }
                        },
                        "id": 1,
                        "login": "j.sheppard",
                        "firstName": "John",
                        "lastName": "Sheppard",
                        "email": "shep@mail.com",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    },
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/2",
                                "title": "Jim Sheppard - j.sheppard2"
                            },
                            "lock": {
                                "href": "/api/v3/users/2/lock",
                                "title": "Set lock on j.sheppard2"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/2",
                                "title": "Delete j.sheppard2"
                                "method": "DELETE"
                            }
                        },
                        "id": 2,
                        "login": "j.sheppard2",
                        "firstName": "Jim",
                        "lastName": "Sheppard",
                        "email": "shep@mail.net",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    }]
                }
            }

## Available assignees [GET]

Gets a list of users that can be assigned to work packages in the given project.

+ Parameters
    + project_id (required, integer, `1`) ... Project id

+ Response 200 (application/hal+json)

    [Available Assignees][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the assignable users for this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }

## Available Responsibles [/api/v3/projects/{project_id}/work_packages/available_responsibles]

+ Model
    + Body

            {
                "_links": {
                    "self": { "href": "/api/v3/projects/42/work_packages/available_responsibles" }
                },
                "total": 2,
                "count": 2,
                "_type": "Collection",
                "_embedded": {
                  "elements": [
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/1",
                                "title": "John Sheppard - j.sheppard"
                            },
                            "lock": {
                                "href": "/api/v3/users/1/lock",
                                "title": "Set lock on j.sheppard"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/1",
                                "title": "Delete j.sheppard"
                                "method": "DELETE"
                            }
                        },
                        "id": 1,
                        "login": "j.sheppard",
                        "firstName": "John",
                        "lastName": "Sheppard",
                        "email": "shep@mail.com",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    },
                    {
                        "_type": "User",
                        "_links": {
                            "self": {
                                "href": "/api/v3/users/2",
                                "title": "Jim Sheppard - j.sheppard2"
                            },
                            "lock": {
                                "href": "/api/v3/users/2/lock",
                                "title": "Set lock on j.sheppard2"
                                "method": "POST"
                            },
                            "delete": {
                                "href": "/api/v3/users/2",
                                "title": "Delete j.sheppard2"
                                "method": "DELETE"
                            }
                        },
                        "id": 2,
                        "login": "j.sheppard2",
                        "firstName": "Jim",
                        "lastName": "Sheppard",
                        "email": "shep@mail.net",
                        "avatar": "https://gravatar/avatar",
                        "status": "active",
                        "createdAt": "2014-05-21T08:51:20Z",
                        "updatedAt": "2014-05-21T08:51:20Z"
                    }]
                }
            }

## Available responsibles [GET]

Gets a list of users that can be assigned as the responsible of a work package in the given project.

+ Parameters
    + project_id (required, integer, `1`) ... Project id

+ Response 200 (application/hal+json)

    [Available Responsibles][]

+ Response 403 (application/hal+json)

    Returned if the client does not have sufficient permissions.

    **Required permission:** view work packages

    *Note that you will only receive this error, if you are at least allowed to see the corresponding project.*

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:MissingPermission",
                "message": "You are not allowed to see the users available as responsible for this project."
            }

+ Response 404 (application/hal+json)

    Returned if the project does not exist or the client does not have sufficient permissions to see it.

    **Required permission:** view project

    + Body

            {
                "_type": "Error",
                "errorIdentifier": "urn:openproject-org:api:v3:errors:NotFound",
                "message": "The specified project does not exist."
            }