nedb/docs/Persistence.md

Persistence

Handle every persistence-related task

Kind: global class

• Persistence
  • new Persistence()
  • instance
    • .persistCachedDatabase(callback)
    • .persistCachedDatabaseAsync() ⇒ Promise.<void>
    • .compactDatafile([callback])
    • .compactDatafileAsync()
    • .setAutocompactionInterval(interval)
    • .stopAutocompaction()
    • .persistNewState(newDocs, [callback])
    • .persistNewStateAsync(newDocs) ⇒ Promise
    • .treatRawData(rawData) ⇒ Object
    • .treatRawStream(rawStream, cb)
    • .treatRawStreamAsync(rawStream) ⇒ Promise.<{data: Array.<document>, indexes: Object.<string, rawIndex>}>
    • .loadDatabase(callback)
    • .loadDatabaseAsync() ⇒ Promise.<void>
  • static
    • .ensureDirectoryExists(dir, [callback])
    • .ensureDirectoryExistsAsync(dir) ⇒ Promise.<void>
    • .getNWAppFilename(appName, relativeFilename) ⇒ string
  • inner
    • ~treatRawStreamCallback : function

new Persistence()

Create a new Persistence object for database options.db

Param	Type	Description
options.db	Datastore
[options.corruptAlertThreshold]	Number	Optional, threshold after which an alert is thrown if too much data is corrupt
[options.nodeWebkitAppName]	string	Optional, specify the name of your NW app if you want options.filename to be relative to the directory where Node Webkit stores application data such as cookies and local storage (the best place to store data in my opinion)
[options.beforeDeserialization]	function	Hook you can use to transform data after it was serialized and before it is written to disk.
[options.afterSerialization]	function	Inverse of afterSerialization.

persistence.persistCachedDatabase(callback)

Persist cached database This serves as a compaction function since the cache always contains only the number of documents in the collection while the data file is append-only so it may grow larger This is an internal function, use compactDataFile which uses the executor

Kind: instance method of Persistence

Param	Type	Description
callback	NoParamCallback	Optional callback, signature: err

persistence.persistCachedDatabaseAsync() ⇒ Promise.<void>

Persist cached database This serves as a compaction function since the cache always contains only the number of documents in the collection while the data file is append-only so it may grow larger This is an internal function, use compactDataFileAsync which uses the executor

Kind: instance method of Persistence

persistence.compactDatafile([callback])

Queue a rewrite of the datafile

Kind: instance method of Persistence

Param	Type	Default	Description
[callback]	NoParamCallback	() => {}	Optional callback, signature: err

persistence.compactDatafileAsync()

Queue a rewrite of the datafile

Kind: instance method of Persistence

persistence.setAutocompactionInterval(interval)

Set automatic compaction every interval ms

Kind: instance method of Persistence

Param	Type	Description
interval	Number	in milliseconds, with an enforced minimum of 5 seconds

persistence.stopAutocompaction()

Stop autocompaction (do nothing if autocompaction was not running)

Kind: instance method of Persistence

persistence.persistNewState(newDocs, [callback])

Persist new state for the given newDocs (can be insertion, update or removal) Use an append-only format

Kind: instance method of Persistence

Param	Type	Default	Description
newDocs	Array.<string>		Can be empty if no doc was updated/removed
[callback]	NoParamCallback	() => {}	Optional, signature: err

persistence.persistNewStateAsync(newDocs) ⇒ Promise

Persist new state for the given newDocs (can be insertion, update or removal) Use an append-only format

Kind: instance method of Persistence

Param	Type	Description
newDocs	Array.<document>	Can be empty if no doc was updated/removed

persistence.treatRawData(rawData) ⇒ Object

From a database's raw data, return the corresponding machine understandable collection

Kind: instance method of Persistence

Param	Type	Description
rawData	string	database file

persistence.treatRawStream(rawStream, cb)

From a database's raw data stream, return the corresponding machine understandable collection

Kind: instance method of Persistence

Param	Type
rawStream	Readable
cb	treatRawStreamCallback

persistence.treatRawStreamAsync(rawStream) ⇒ Promise.<{data: Array.<document>, indexes: Object.<string, rawIndex>}>

From a database's raw data stream, return the corresponding machine understandable collection

Kind: instance method of Persistence

Param	Type
rawStream	Readable

persistence.loadDatabase(callback)

Load the database

1. Create all indexes
2. Insert all data
3. Compact the database This means pulling data out of the data file or creating it if it doesn't exist Also, all data is persisted right away, which has the effect of compacting the database file This operation is very quick at startup for a big collection (60ms for ~10k docs)

Kind: instance method of Persistence

Param	Type	Description
callback	NoParamCallback	Optional callback, signature: err

persistence.loadDatabaseAsync() ⇒ Promise.<void>

Load the database

1. Create all indexes
2. Insert all data
3. Compact the database This means pulling data out of the data file or creating it if it doesn't exist Also, all data is persisted right away, which has the effect of compacting the database file This operation is very quick at startup for a big collection (60ms for ~10k docs)

Kind: instance method of Persistence

Persistence.ensureDirectoryExists(dir, [callback])

Check if a directory stat and create it on the fly if it is not the case

Kind: static method of Persistence

Param	Type	Default	Description
dir	string
[callback]	NoParamCallback	() => {}	optional callback, signature: err

Persistence.ensureDirectoryExistsAsync(dir) ⇒ Promise.<void>

Check if a directory stat and create it on the fly if it is not the case

Kind: static method of Persistence

Param	Type
dir	string

Persistence.getNWAppFilename(appName, relativeFilename) ⇒ string

Deprecated

Return the path the datafile if the given filename is relative to the directory where Node Webkit stores data for this application. Probably the best place to store data

Kind: static method of Persistence

Param	Type
appName	string
relativeFilename	string

Persistence~treatRawStreamCallback : function

Kind: inner typedef of Persistence

Param	Type
err	Error
data	Object