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cursor.js
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cursor.js
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"use strict";
var inherits = require('util').inherits
, f = require('util').format
, toError = require('./utils').toError
, getSingleProperty = require('./utils').getSingleProperty
, formattedOrderClause = require('./utils').formattedOrderClause
, handleCallback = require('./utils').handleCallback
, Logger = require('mongodb-core').Logger
, EventEmitter = require('events').EventEmitter
, ReadPreference = require('./read_preference')
, MongoError = require('mongodb-core').MongoError
, Readable = require('stream').Readable || require('readable-stream').Readable
, CoreCursor = require('mongodb-core').Cursor
, Query = require('mongodb-core').Query
, CoreReadPreference = require('mongodb-core').ReadPreference;
/**
* @fileOverview The **Cursor** class is an internal class that embodies a cursor on MongoDB
* allowing for iteration over the results returned from the underlying query. It supports
* one by one document iteration, conversion to an array or can be iterated as a Node 0.10.X
* or higher stream
*
* **CURSORS Cannot directly be instantiated**
* @example
* var MongoClient = require('mongodb').MongoClient,
* test = require('assert');
* // Connection url
* var url = 'mongodb://localhost:27017/test';
* // Connect using MongoClient
* MongoClient.connect(url, function(err, db) {
* // Create a collection we want to drop later
* var col = db.collection('createIndexExample1');
* // Insert a bunch of documents
* col.insert([{a:1, b:1}
* , {a:2, b:2}, {a:3, b:3}
* , {a:4, b:4}], {w:1}, function(err, result) {
* test.equal(null, err);
*
* // Show that duplicate records got dropped
* col.find({}).toArray(function(err, items) {
* test.equal(null, err);
* test.equal(4, items.length);
* db.close();
* });
* });
* });
*/
/**
* Namespace provided by the mongodb-core and node.js
* @external CoreCursor
* @external Readable
*/
// Flags allowed for cursor
var flags = ['tailable', 'oplogReplay', 'noCursorTimeout', 'awaitData', 'exhaust', 'partial'];
/**
* Creates a new Cursor instance (INTERNAL TYPE, do not instantiate directly)
* @class
* @extends external:CoreCursor
* @extends external:Readable
* @property {string} sortValue Cursor query sort setting.
* @property {boolean} timeout Is Cursor able to time out.
* @property {ReadPreference} readPreference Get cursor ReadPreference.
* @fires Cursor#data
* @fires Cursor#end
* @fires Cursor#close
* @fires Cursor#readable
* @return {Cursor} a Cursor instance.
* @example
* Some example
*/
var Cursor = function(bson, ns, cmd, options, topology, topologyOptions) {
CoreCursor.apply(this, Array.prototype.slice.call(arguments, 0));
var self = this;
var state = Cursor.INIT;
var streamOptions = {};
// Tailable cursor options
var numberOfRetries = options.numberOfRetries || 5;
var tailableRetryInterval = options.tailableRetryInterval || 500;
var currentNumberOfRetries = numberOfRetries;
// MaxTimeMS
var maxTimeMS = null;
// Set up
Readable.call(this, {objectMode: true});
// Internal cursor state
this.s = {
// MaxTimeMS
maxTimeMS: null
// Tailable cursor options
, numberOfRetries: numberOfRetries
, tailableRetryInterval: tailableRetryInterval
, currentNumberOfRetries: currentNumberOfRetries
// State
, state: state
// Stream options
, streamOptions: streamOptions
// BSON
, bson: bson
// Namespace
, ns: ns
// Command
, cmd: cmd
// Options
, options: options
// Topology
, topology: topology
// Topology options
, topologyOptions: topologyOptions
}
// Legacy fields
this.timeout = self.s.options.noCursorTimeout == true;
this.sortValue = self.s.cmd.sort;
this.readPreference = self.s.options.readPreference;
}
/**
* Cursor stream data event, fired for each document in the cursor.
*
* @event Cursor#data
* @type {object}
*/
/**
* Cursor stream end event
*
* @event Cursor#end
* @type {null}
*/
/**
* Cursor stream close event
*
* @event Cursor#close
* @type {null}
*/
/**
* Cursor stream readable event
*
* @event Cursor#readable
* @type {null}
*/
// Inherit from Readable
inherits(Cursor, Readable);
for(var name in CoreCursor.prototype) {
Cursor.prototype[name] = CoreCursor.prototype[name];
}
/**
* Set the cursor query
* @method
* @param {object} filter The filter object used for the cursor.
* @return {Cursor}
*/
Cursor.prototype.filter = function(filter) {
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
this.s.cmd.query = filter;
return this;
}
/**
* Add a cursor flag to the cursor
* @method
* @param {string} flag The flag to set, must be one of following ['tailable', 'oplogReplay', 'noCursorTimeout', 'awaitData', 'exhaust', 'partial'].
* @param {boolean} value The flag boolean value.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.addCursorFlag = function(flag, value) {
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
if(flags.indexOf(flag) == -1) throw new MongoError(f("flag % not a supported flag %s", flag, flags));
if(typeof value != 'boolean') throw new MongoError(f("flag % must be a boolean value", flag));
this.s.cmd[flag] = value;
return this;
}
/**
* Add a query modifier to the cursor query
* @method
* @param {string} name The query modifier (must start with $, such as $orderby etc)
* @param {boolean} value The flag boolean value.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.addQueryModifier = function(name, value) {
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
if(name[0] != '$') throw new MongoError(f("%s is not a valid query modifier"));
// Strip of the $
var field = name.substr(1);
// Set on the command
this.s.cmd[field] = value;
// Deal with the special case for sort
if(field == 'orderby') this.s.cmd.sort = this.s.cmd[field];
return this;
}
/**
* Add a comment to the cursor query allowing for tracking the comment in the log.
* @method
* @param {string} value The comment attached to this query.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.comment = function(value) {
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
this.s.cmd.comment = value;
return this;
}
/**
* Set a maxTimeMS on the cursor query, allowing for hard timeout limits on queries (Only supported on MongoDB 2.6 or higher)
* @method
* @param {number} value Number of milliseconds to wait before aborting the query.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.maxTimeMS = function(value) {
if(typeof value != 'number') throw new MongoError("maxTimeMS must be a number");
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
this.s.maxTimeMS = value;
this.s.cmd.maxTimeMS = value;
return this;
}
Cursor.prototype.maxTimeMs = Cursor.prototype.maxTimeMS;
/**
* Sets a field projection for the query.
* @method
* @param {object} value The field projection object.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.project = function(value) {
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
this.s.cmd.fields = value;
return this;
}
/**
* Sets the sort order of the cursor query.
* @method
* @param {(string|array|object)} keyOrList The key or keys set for the sort.
* @param {number} [direction] The direction of the sorting (1 or -1).
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.sort = function(keyOrList, direction) {
if(this.s.options.tailable) throw new MongoError("Tailable cursor doesn't support sorting");
if(this.s.state == Cursor.CLOSED || this.s.state == Cursor.OPEN || this.isDead()) throw new MongoError("Cursor is closed");
var order = keyOrList;
if(direction != null) {
order = [[keyOrList, direction]];
}
this.s.cmd.sort = order;
this.sortValue = order;
return this;
}
/**
* Set the batch size for the cursor.
* @method
* @param {number} value The batchSize for the cursor.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.batchSize = function(value) {
if(this.s.options.tailable) throw new MongoError("Tailable cursor doesn't support limit");
if(this.s.state == Cursor.CLOSED || this.isDead()) throw new MongoError("Cursor is closed");
if(typeof value != 'number') throw new MongoError("batchSize requires an integer");
this.s.cmd.batchSize = value;
this.setCursorBatchSize(value);
return this;
}
/**
* Set the limit for the cursor.
* @method
* @param {number} value The limit for the cursor query.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.limit = function(value) {
if(this.s.options.tailable) throw new MongoError("Tailable cursor doesn't support limit");
if(this.s.state == Cursor.OPEN || this.s.state == Cursor.CLOSED || this.isDead()) throw new MongoError("Cursor is closed");
if(typeof value != 'number') throw new MongoError("limit requires an integer");
this.s.cmd.limit = value;
// this.cursorLimit = value;
this.setCursorLimit(value);
return this;
}
/**
* Set the skip for the cursor.
* @method
* @param {number} value The skip for the cursor query.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.skip = function(value) {
if(this.s.options.tailable) throw new MongoError("Tailable cursor doesn't support skip");
if(this.s.state == Cursor.OPEN || this.s.state == Cursor.CLOSED || this.isDead()) throw new MongoError("Cursor is closed");
if(typeof value != 'number') throw new MongoError("skip requires an integer");
this.s.cmd.skip = value;
this.setCursorSkip(value);
return this;
}
/**
* The callback format for results
* @callback Cursor~resultCallback
* @param {MongoError} error An error instance representing the error during the execution.
* @param {(object|null)} result The result object if the command was executed successfully.
*/
/**
* Get the next available document from the cursor, returns null if no more documents are available.
* @function external:CoreCursor#next
* @param {Cursor~resultCallback} callback The result callback.
* @throws {MongoError}
* @return {null}
*/
/**
* Set the new batchSize of the cursor
* @function Cursor.prototype.setBatchSize
* @param {number} value The new batchSize for the cursor
* @return {null}
*/
/**
* Get the batchSize of the cursor
* @function Cursor.prototype.batchSize
* @param {number} value The current batchSize for the cursor
* @return {null}
*/
/**
* Set the new skip value of the cursor
* @function Cursor.prototype.setCursorSkip
* @param {number} value The new skip for the cursor
* @return {null}
*/
/**
* Get the skip value of the cursor
* @function Cursor.prototype.cursorSkip
* @param {number} value The current skip value for the cursor
* @return {null}
*/
/**
* Set the new limit value of the cursor
* @function Cursor.prototype.setCursorLimit
* @param {number} value The new limit for the cursor
* @return {null}
*/
/**
* Get the limit value of the cursor
* @function Cursor.prototype.cursorLimit
* @param {number} value The current limit value for the cursor
* @return {null}
*/
/**
* Clone the cursor
* @function external:CoreCursor#clone
* @return {Cursor}
*/
/**
* Resets the cursor
* @function external:CoreCursor#rewind
* @return {null}
*/
/**
* Get the next available document from the cursor, returns null if no more documents are available.
* @method
* @param {Cursor~resultCallback} callback The result callback.
* @throws {MongoError}
* @deprecated
* @return {null}
*/
Cursor.prototype.nextObject = function(callback) {
var self = this;
if(this.s.state == Cursor.CLOSED || self.isDead()) return handleCallback(callback, new MongoError("Cursor is closed"));
if(this.s.state == Cursor.INIT && this.s.cmd.sort) {
try {
this.s.cmd.sort = formattedOrderClause(this.s.cmd.sort);
} catch(err) {
return handleCallback(callback, err);
}
}
// Get the next object
self.next(function(err, doc) {
if(err && err.tailable && self.s.currentNumberOfRetries == 0) return callback(err);
if(err && err.tailable && self.s.currentNumberOfRetries > 0) {
self.s.currentNumberOfRetries = self.s.currentNumberOfRetries - 1;
return setTimeout(function() {
self.nextObject(callback);
}, self.s.tailableRetryInterval);
}
self.s.state = Cursor.OPEN;
if(err) return handleCallback(callback, err);
handleCallback(callback, null, doc);
});
}
// Trampoline emptying the number of retrieved items
// without incurring a nextTick operation
var loop = function(self, callback) {
// No more items we are done
if(self.bufferedCount() == 0) return;
// Get the next document
self.next(callback);
// Loop
return loop;
}
/**
* Iterates over all the documents for this cursor. As with **{cursor.toArray}**,
* not all of the elements will be iterated if this cursor had been previouly accessed.
* In that case, **{cursor.rewind}** can be used to reset the cursor. However, unlike
* **{cursor.toArray}**, the cursor will only hold a maximum of batch size elements
* at any given time if batch size is specified. Otherwise, the caller is responsible
* for making sure that the entire result can fit the memory.
* @method
* @deprecated
* @param {Cursor~resultCallback} callback The result callback.
* @throws {MongoError}
* @return {null}
*/
Cursor.prototype.each = function(callback) {
// Rewind cursor state
this.rewind();
// Set current cursor to INIT
this.s.state = Cursor.INIT;
// Run the query
_each(this, callback);
};
// Run the each loop
var _each = function(self, callback) {
if(!callback) throw new MongoError('callback is mandatory');
if(self.isNotified()) return;
if(self.s.state == Cursor.CLOSED || self.isDead()) {
return handleCallback(callback, new MongoError("Cursor is closed"), null);
}
if(self.s.state == Cursor.INIT) self.s.state = Cursor.OPEN;
// Define function to avoid global scope escape
var fn = null;
// Trampoline all the entries
if(self.bufferedCount() > 0) {
while(fn = loop(self, callback)) fn(self, callback);
_each(self, callback);
} else {
self.next(function(err, item) {
if(err) return handleCallback(callback, err);
if(item == null) {
self.s.state = Cursor.CLOSED;
return handleCallback(callback, null, null);
}
if(handleCallback(callback, null, item) == false) return;
_each(self, callback);
})
}
}
/**
* The callback format for the forEach iterator method
* @callback Cursor~iteratorCallback
* @param {Object} doc An emitted document for the iterator
*/
/**
* The callback error format for the forEach iterator method
* @callback Cursor~endCallback
* @param {MongoError} error An error instance representing the error during the execution.
*/
/**
* Iterates over all the documents for this cursor using the iterator, callback pattern.
* @method
* @param {Cursor~iteratorCallback} iterator The iteration callback.
* @param {Cursor~endCallback} callback The end callback.
* @throws {MongoError}
* @return {null}
*/
Cursor.prototype.forEach = function(iterator, callback) {
this.each(function(err, doc){
if(err) { callback(err); return false; }
if(doc != null) { iterator(doc); return true; }
if(doc == null && callback) {
var internalCallback = callback;
callback = null;
internalCallback(null);
return false;
}
});
}
/**
* Set the ReadPreference for the cursor.
* @method
* @param {(string|ReadPreference)} readPreference The new read preference for the cursor.
* @throws {MongoError}
* @return {Cursor}
*/
Cursor.prototype.setReadPreference = function(r) {
if(this.s.state != Cursor.INIT) throw new MongoError('cannot change cursor readPreference after cursor has been accessed');
if(r instanceof ReadPreference) {
this.s.options.readPreference = new CoreReadPreference(r.mode, r.tags);
} else {
this.s.options.readPreference = new CoreReadPreference(r);
}
return this;
}
/**
* The callback format for results
* @callback Cursor~toArrayResultCallback
* @param {MongoError} error An error instance representing the error during the execution.
* @param {object[]} documents All the documents the satisfy the cursor.
*/
/**
* Returns an array of documents. The caller is responsible for making sure that there
* is enough memory to store the results. Note that the array only contain partial
* results when this cursor had been previouly accessed. In that case,
* cursor.rewind() can be used to reset the cursor.
* @method
* @param {Cursor~toArrayResultCallback} callback The result callback.
* @throws {MongoError}
* @return {null}
*/
Cursor.prototype.toArray = function(callback) {
var self = this;
if(!callback) throw new MongoError('callback is mandatory');
if(self.s.options.tailable) return handleCallback(callback, new MongoError("Tailable cursor cannot be converted to array"), null);
var items = [];
// Reset cursor
this.rewind();
self.s.state = Cursor.INIT;
// Fetch all the documents
var fetchDocs = function() {
self.next(function(err, doc) {
if(err) return handleCallback(callback, err);
if(doc == null) {
self.s.state = Cursor.CLOSED;
return handleCallback(callback, null, items);
}
// Add doc to items
items.push(doc)
// Get all buffered objects
if(self.bufferedCount() > 0) {
var a = self.readBufferedDocuments(self.bufferedCount())
items = items.concat(a);
}
// Attempt a fetch
fetchDocs();
})
}
fetchDocs();
}
/**
* The callback format for results
* @callback Cursor~countResultCallback
* @param {MongoError} error An error instance representing the error during the execution.
* @param {number} count The count of documents.
*/
/**
* Get the count of documents for this cursor
* @method
* @param {boolean} applySkipLimit Should the count command apply limit and skip settings on the cursor or in the passed in options.
* @param {object} [options=null] Optional settings.
* @param {number} [options.skip=null] The number of documents to skip.
* @param {number} [options.limit=null] The maximum amounts to count before aborting.
* @param {number} [options.maxTimeMS=null] Number of miliseconds to wait before aborting the query.
* @param {string} [options.hint=null] An index name hint for the query.
* @param {(ReadPreference|string)} [options.readPreference=null] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
* @param {Cursor~countResultCallback} callback The result callback.
* @return {null}
*/
Cursor.prototype.count = function(applySkipLimit, opts, callback) {
var self = this;
if(typeof opts == 'function') callback = opts, opts = {};
opts = opts || {};
if(self.s.cmd.query == null) callback(new MongoError("count can only be used with find command"));
if(typeof applySkipLimit == 'function') {
callback = applySkipLimit;
applySkipLimit = true;
}
var opts = {};
if(applySkipLimit) {
if(typeof this.cursorSkip() == 'number') opts.skip = this.cursorSkip();
if(typeof this.cursorLimit() == 'number') opts.limit = this.cursorLimit();
}
// Command
var delimiter = self.s.ns.indexOf('.');
var command = {
'count': self.s.ns.substr(delimiter+1), 'query': self.s.cmd.query
}
// If maxTimeMS set
if(typeof maxTimeMS == 'number') {
command.maxTimeMS = self.s.maxTimeMS;
}
// Get a server
var server = self.s.topology.getServer(opts);
// Get a connection
var connection = self.s.topology.getConnection(opts);
// Get the callbacks
var callbacks = server.getCallbacks();
// Merge in any options
if(opts.skip) command.skip = opts.skip;
if(opts.limit) command.limit = opts.limit;
if(self.s.options.hint) command.hint = self.s.options.hint;
// Build Query object
var query = new Query(self.s.bson, f("%s.$cmd", self.s.ns.substr(0, delimiter)), command, {
numberToSkip: 0, numberToReturn: -1
, checkKeys: false
});
// Set up callback
callbacks.register(query.requestId, function(err, result) {
if(err) return handleCallback(callback, err);
if(result.documents.length == 1
&& (result.documents[0].errmsg
|| result.documents[0].err
|| result.documents[0]['$err'])) return callback(MongoError.create(result.documents[0]));
handleCallback(callback, null, result.documents[0].n);
});
// Write the initial command out
connection.write(query.toBin());
};
/**
* Close the cursor, sending a KillCursor command and emitting close.
* @method
* @param {Cursor~resultCallback} [callback] The result callback.
* @return {null}
*/
Cursor.prototype.close = function(callback) {
this.s.state = Cursor.CLOSED;
// Kill the cursor
this.kill();
// Emit the close event for the cursor
this.emit('close');
// Callback if provided
if(callback) return handleCallback(callback, null, this);
}
/**
* Is the cursor closed
* @method
* @return {boolean}
*/
Cursor.prototype.isClosed = function() {
return this.isDead();
}
Cursor.prototype.destroy = function(err) {
this.pause();
this.close();
if(err) this.emit('error', err);
}
/**
* Return a modified Readable stream including a possible transform method.
* @method
* @param {object} [options=null] Optional settings.
* @param {function} [options.transform=null] A transformation method applied to each document emitted by the stream.
* @return {Cursor}
*/
Cursor.prototype.stream = function(options) {
this.s.streamOptions = options || {};
return this;
}
/**
* Execute the explain for the cursor
* @method
* @param {Cursor~resultCallback} [callback] The result callback.
* @return {null}
*/
Cursor.prototype.explain = function(callback) {
this.s.cmd.explain = true;
this.next(callback);
}
Cursor.prototype._read = function(n) {
var self = this;
if(self.s.state == Cursor.CLOSED || self.isDead()) {
// options.db.removeListener('close', closeListener);
return self.push(null);
}
// Get the next item
self.nextObject(function(err, result) {
if(err) {
if(!self.isDead()) self.destroy();
return self.push(null);
}
// If we provided a transformation method
if(typeof self.s.streamOptions.transform == 'function' && result != null) {
return self.push(self.s.streamOptions.transform(result));
}
// Return the result
self.push(result);
});
}
Object.defineProperty(Cursor.prototype, 'namespace', {
enumerable: true,
get: function() {
if (!this || !this.s) {
return null;
}
// TODO: refactor this logic into core
var ns = this.s.ns || '';
var firstDot = ns.indexOf('.');
if (firstDot < 0) {
return {
database: this.s.ns,
collection: ''
};
}
return {
database: ns.substr(0, firstDot),
collection: ns.substr(firstDot + 1)
};
}
});
/**
* The read() method pulls some data out of the internal buffer and returns it. If there is no data available, then it will return null.
* @function external:Readable#read
* @param {number} size Optional argument to specify how much data to read.
* @return {(String | Buffer | null)}
*/
/**
* Call this function to cause the stream to return strings of the specified encoding instead of Buffer objects.
* @function external:Readable#setEncoding
* @param {string} encoding The encoding to use.
* @return {null}
*/
/**
* This method will cause the readable stream to resume emitting data events.
* @function external:Readable#resume
* @return {null}
*/
/**
* This method will cause a stream in flowing-mode to stop emitting data events. Any data that becomes available will remain in the internal buffer.
* @function external:Readable#pause
* @return {null}
*/
/**
* This method pulls all the data out of a readable stream, and writes it to the supplied destination, automatically managing the flow so that the destination is not overwhelmed by a fast readable stream.
* @function external:Readable#pipe
* @param {Writable} destination The destination for writing data
* @param {object} [options] Pipe options
* @return {null}
*/
/**
* This method will remove the hooks set up for a previous pipe() call.
* @function external:Readable#unpipe
* @param {Writable} [destination] The destination for writing data
* @return {null}
*/
/**
* This is useful in certain cases where a stream is being consumed by a parser, which needs to "un-consume" some data that it has optimistically pulled out of the source, so that the stream can be passed on to some other party.
* @function external:Readable#unshift
* @param {(Buffer|string)} chunk Chunk of data to unshift onto the read queue.
* @return {null}
*/
/**
* Versions of Node prior to v0.10 had streams that did not implement the entire Streams API as it is today. (See "Compatibility" below for more information.)
* @function external:Readable#wrap
* @param {Stream} stream An "old style" readable stream.
* @return {null}
*/
Cursor.INIT = 0;
Cursor.OPEN = 1;
Cursor.CLOSED = 2;
Cursor.GET_MORE = 3;
module.exports = Cursor;