The JavaScript Database, for Node.js, nw.js, electron and the browser
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nedb/lib/datastore.js

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var customUtils = require('./customUtils')
, model = require('./model')
, async = require('async')
, Executor = require('./executor')
, Index = require('./indexes')
, util = require('util')
, _ = require('underscore')
, Persistence = require('./persistence')
;
/**
* Create a new collection
* @param {String} options.filename Optional, datastore will be in-memory only if not provided
* @param {Boolean} options.inMemoryOnly Optional, default to false
* @param {Boolean} options.nodeWebkitAppName 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)
* @param {Boolean} options.autoload Optional, defaults to false
*/
function Datastore (options) {
var filename;
// Retrocompatibility with v0.6 and before
if (typeof options === 'string') {
filename = options;
this.inMemoryOnly = false; // Default
} else {
options = options || {};
filename = options.filename;
this.inMemoryOnly = options.inMemoryOnly || false;
this.autoload = options.autoload || false;
}
// Determine whether in memory or persistent
if (!filename || typeof filename !== 'string' || filename.length === 0) {
this.filename = null;
this.inMemoryOnly = true;
} else {
this.filename = filename;
}
// Persistence handling
this.persistence = new Persistence({ db: this, nodeWebkitAppName: options.nodeWebkitAppName });
// This new executor is ready if we don't use persistence
// If we do, it will only be ready once loadDatabase is called
this.executor = new Executor();
if (this.inMemoryOnly) { this.executor.ready = true; }
// Indexed by field name, dot notation can be used
// _id is always indexed and since _ids are generated randomly the underlying
// binary is always well-balanced
this.indexes = {};
this.indexes._id = new Index({ fieldName: '_id', unique: true });
if (this.autoload) { this.loadDatabase(); }
}
/**
* Load the database from the datafile, and trigger the execution of buffered commands if any
*/
Datastore.prototype.loadDatabase = function () {
this.executor.push({ this: this.persistence, fn: this.persistence.loadDatabase, arguments: arguments }, true);
};
/**
* Get an array of all the data in the database
*/
Datastore.prototype.getAllData = function () {
return this.indexes._id.getAll();
};
/**
* Reset all currently defined indexes
*/
Datastore.prototype.resetIndexes = function (newData) {
var self = this;
Object.keys(this.indexes).forEach(function (i) {
self.indexes[i].reset(newData);
});
};
/**
* Ensure an index is kept for this field. Same parameters as lib/indexes
* For now this function is synchronous, we need to test how much time it takes
* We use an async API for consistency with the rest of the code
* @param {String} options.fieldName
* @param {Boolean} options.unique
* @param {Boolean} options.sparse
* @param {Function} cb Optional callback, signature: err
*/
Datastore.prototype.ensureIndex = function (options, cb) {
var callback = cb || function () {};
options = options || {};
if (!options.fieldName) { return callback({ missingFieldName: true }); }
if (this.indexes[options.fieldName]) { return callback(null); }
this.indexes[options.fieldName] = new Index(options);
try {
this.indexes[options.fieldName].insert(this.getAllData());
} catch (e) {
delete this.indexes[options.fieldName];
return callback(e);
}
return callback(null);
};
/**
* Add one or several document(s) to all indexes
*/
Datastore.prototype.addToIndexes = function (doc) {
var i, failingIndex, error
, keys = Object.keys(this.indexes)
;
for (i = 0; i < keys.length; i += 1) {
try {
this.indexes[keys[i]].insert(doc);
} catch (e) {
failingIndex = i;
error = e;
break;
}
}
// If an error happened, we need to rollback the insert on all other indexes
if (error) {
for (i = 0; i < failingIndex; i += 1) {
this.indexes[keys[i]].remove(doc);
}
throw error;
}
};
/**
* Remove one or several document(s) from all indexes
*/
Datastore.prototype.removeFromIndexes = function (doc) {
var self = this;
Object.keys(this.indexes).forEach(function (i) {
self.indexes[i].remove(doc);
});
};
/**
* Update one or several documents in all indexes
* To update multiple documents, oldDoc must be an array of { oldDoc, newDoc } pairs
* If one update violates a constraint, all changes are rolled back
*/
Datastore.prototype.updateIndexes = function (oldDoc, newDoc) {
var i, failingIndex, error
, keys = Object.keys(this.indexes)
;
for (i = 0; i < keys.length; i += 1) {
try {
this.indexes[keys[i]].update(oldDoc, newDoc);
} catch (e) {
failingIndex = i;
error = e;
break;
}
}
// If an error happened, we need to rollback the update on all other indexes
if (error) {
for (i = 0; i < failingIndex; i += 1) {
this.indexes[keys[i]].revertUpdate(oldDoc, newDoc);
}
throw error;
}
};
/**
* Return the list of candidates for a given query
* Crude implementation for now, we return the candidates given by the first usable index if any
* We try the following query types, in this order: basic match, $in match, comparison match
* One way to make it better would be to enable the use of multiple indexes if the first usable index
* returns too much data. I may do it in the future.
*/
Datastore.prototype.getCandidates = function (query) {
var indexNames = Object.keys(this.indexes)
, usableQueryKeys;
// For a basic match
usableQueryKeys = [];
Object.keys(query).forEach(function (k) {
if (typeof query[k] === 'string' || typeof query[k] === 'number' || typeof query[k] === 'boolean' || util.isDate(query[k]) || query[k] === null) {
usableQueryKeys.push(k);
}
});
usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
if (usableQueryKeys.length > 0) {
return this.indexes[usableQueryKeys[0]].getMatching(query[usableQueryKeys[0]]);
}
// For a $in match
usableQueryKeys = [];
Object.keys(query).forEach(function (k) {
if (query[k] && query[k].hasOwnProperty('$in')) {
usableQueryKeys.push(k);
}
});
usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
if (usableQueryKeys.length > 0) {
return this.indexes[usableQueryKeys[0]].getMatching(query[usableQueryKeys[0]].$in);
}
// For a comparison match
usableQueryKeys = [];
Object.keys(query).forEach(function (k) {
if (query[k] && (query[k].hasOwnProperty('$lt') || query[k].hasOwnProperty('$lte') || query[k].hasOwnProperty('$gt') || query[k].hasOwnProperty('$gte'))) {
usableQueryKeys.push(k);
}
});
usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
if (usableQueryKeys.length > 0) {
return this.indexes[usableQueryKeys[0]].getBetweenBounds(query[usableQueryKeys[0]]);
}
// By default, return all the DB data
return this.getAllData();
};
/**
* Insert a new document
* @param {Function} cb Optional callback, signature: err, insertedDoc
*
* @api private Use Datastore.insert which has the same signature
*/
Datastore.prototype._insert = function (newDoc, cb) {
var callback = cb || function () {}
, self = this
, insertedDoc
;
// Ensure the document has the right format
try {
newDoc._id = customUtils.uid(16);
model.checkObject(newDoc);
insertedDoc = model.deepCopy(newDoc);
} catch (e) {
return callback(e);
}
// Insert in all indexes (also serves to ensure uniqueness)
try { self.addToIndexes(insertedDoc); } catch (e) { return callback(e); }
this.persistence.persistNewState([newDoc], function (err) {
if (err) { return callback(err); }
return callback(null, newDoc);
});
};
Datastore.prototype.insert = function () {
this.executor.push({ this: this, fn: this._insert, arguments: arguments });
};
/**
* Count all documents matching the query
* @param {Object} query MongoDB-style query
*
* @api private Use count
*/
Datastore.prototype._count = function(query, callback) {
var res = 0
, self = this
, candidates = this.getCandidates(query)
, i
;
try {
for (i = 0; i < candidates.length; i += 1) {
if (model.match(candidates[i], query)) {
res++;
}
}
} catch (err) {
return callback(err);
}
return callback(null, res);
}
Datastore.prototype.count = function() {
this.executor.push({this: this, fn: this._count, arguments: arguments });
}
/**
* Find all documents matching the query
* @param {Object} query MongoDB-style query
*
* @api private Use find
*/
Datastore.prototype._find = function (query, callback) {
var res = []
, self = this
, candidates = this.getCandidates(query)
, i
;
try {
for (i = 0; i < candidates.length; i += 1) {
if (model.match(candidates[i], query)) {
res.push(model.deepCopy(candidates[i]));
}
}
} catch (err) {
return callback(err);
}
return callback(null, res);
};
Datastore.prototype.find = function () {
this.executor.push({ this: this, fn: this._find, arguments: arguments });
};
/**
* Find one document matching the query
* @param {Object} query MongoDB-style query
*
* @api private Use findOne
*/
Datastore.prototype._findOne = function (query, callback) {
var self = this
, candidates = this.getCandidates(query)
, i
;
try {
for (i = 0; i < candidates.length; i += 1) {
if (model.match(candidates[i], query)) {
return callback(null, model.deepCopy(candidates[i]));
}
}
} catch (err) {
return callback(err);
}
return callback(null, null);
};
Datastore.prototype.findOne = function () {
this.executor.push({ this: this, fn: this._findOne, arguments: arguments });
};
/**
* Update all docs matching query
* For now, very naive implementation (recalculating the whole database)
* @param {Object} query
* @param {Object} updateQuery
* @param {Object} options Optional options
* options.multi If true, can update multiple documents (defaults to false)
* options.upsert If true, document is inserted if the query doesn't match anything
* @param {Function} cb Optional callback, signature: err, numReplaced, upsert (set to true if the update was in fact an upsert)
*
* @api private Use Datastore.update which has the same signature
*/
Datastore.prototype._update = function (query, updateQuery, options, cb) {
var callback
, self = this
, numReplaced = 0
, multi, upsert
, i
;
if (typeof options === 'function') { cb = options; options = {}; }
callback = cb || function () {};
multi = options.multi !== undefined ? options.multi : false;
upsert = options.upsert !== undefined ? options.upsert : false;
async.waterfall([
function (cb) { // If upsert option is set, check whether we need to insert the doc
if (!upsert) { return cb(); }
self._findOne(query, function (err, doc) {
if (err) { return callback(err); }
if (doc) {
return cb();
} else {
// The upserted document is the query (since for now queries have the same structure as
// documents), modified by the updateQuery
return self._insert(model.modify(query, updateQuery), function (err) {
if (err) { return callback(err); }
return callback(null, 1, true);
});
}
});
}
, function () { // Perform the update
var modifiedDoc
, candidates = self.getCandidates(query)
, modifications = []
;
// Preparing update (if an error is thrown here neither the datafile nor
// the in-memory indexes are affected)
try {
for (i = 0; i < candidates.length; i += 1) {
if (model.match(candidates[i], query) && (multi || numReplaced === 0)) {
numReplaced += 1;
modifiedDoc = model.modify(candidates[i], updateQuery);
modifications.push({ oldDoc: candidates[i], newDoc: modifiedDoc });
}
}
} catch (err) {
return callback(err);
}
// Change the docs in memory
try {
self.updateIndexes(modifications);
} catch (err) {
return callback(err);
}
// Update the datafile
self.persistence.persistNewState(_.pluck(modifications, 'newDoc'), function (err) {
if (err) { return callback(err); }
return callback(null, numReplaced);
});
}
]);
};
Datastore.prototype.update = function () {
this.executor.push({ this: this, fn: this._update, arguments: arguments });
};
/**
* Remove all docs matching the query
* For now very naive implementation (similar to update)
* @param {Object} query
* @param {Object} options Optional options
* options.multi If true, can update multiple documents (defaults to false)
* @param {Function} cb Optional callback, signature: err, numRemoved
*
* @api private Use Datastore.remove which has the same signature
*/
Datastore.prototype._remove = function (query, options, cb) {
var callback
, self = this
, numRemoved = 0
, multi
, removedDocs = []
, candidates = this.getCandidates(query)
;
if (typeof options === 'function') { cb = options; options = {}; }
callback = cb || function () {};
multi = options.multi !== undefined ? options.multi : false;
try {
candidates.forEach(function (d) {
if (model.match(d, query) && (multi || numRemoved === 0)) {
numRemoved += 1;
removedDocs.push({ $$deleted: true, _id: d._id });
self.removeFromIndexes(d);
}
});
} catch (err) { return callback(err); }
self.persistence.persistNewState(removedDocs, function (err) {
if (err) { return callback(err); }
return callback(null, numRemoved);
});
};
Datastore.prototype.remove = function () {
this.executor.push({ this: this, fn: this._remove, arguments: arguments });
};
/*
var db = new Datastore({ inMemoryOnly: true })
//db.ensureIndex({ fieldName: 'tag' });
db.insert({ tag: ['a', 'b', 'c'] }, function () {
db.find({ tag: 'b' }, function (err, item) {
console.log(err);
console.log(item);
});
});
*/
module.exports = Datastore;