/node_modules/mongoose/lib/cursor/QueryCursor.js
https://bitbucket.org/coleman333/smartsite · JavaScript · 311 lines · 164 code · 32 blank · 115 comment · 23 complexity · 3329c1bf0bf07c6c0a8c42da74328f9d MD5 · raw file
- /*!
- * Module dependencies.
- */
- var Readable = require('stream').Readable;
- var eachAsync = require('../services/cursor/eachAsync');
- var helpers = require('../queryhelpers');
- var util = require('util');
- var utils = require('../utils');
- /**
- * A QueryCursor is a concurrency primitive for processing query results
- * one document at a time. A QueryCursor fulfills the Node.js streams3 API,
- * in addition to several other mechanisms for loading documents from MongoDB
- * one at a time.
- *
- * QueryCursors execute the model's pre find hooks, but **not** the model's
- * post find hooks.
- *
- * Unless you're an advanced user, do **not** instantiate this class directly.
- * Use [`Query#cursor()`](/docs/api.html#query_Query-cursor) instead.
- *
- * @param {Query} query
- * @param {Object} options query options passed to `.find()`
- * @inherits Readable
- * @event `cursor`: Emitted when the cursor is created
- * @event `error`: Emitted when an error occurred
- * @event `data`: Emitted when the stream is flowing and the next doc is ready
- * @event `end`: Emitted when the stream is exhausted
- * @api public
- */
- function QueryCursor(query, options) {
- Readable.call(this, { objectMode: true });
- this.cursor = null;
- this.query = query;
- this._transforms = options.transform ? [options.transform] : [];
- var _this = this;
- var model = query.model;
- model.hooks.execPre('find', query, function() {
- model.collection.find(query._conditions, options, function(err, cursor) {
- if (_this._error) {
- cursor.close(function() {});
- _this.listeners('error').length > 0 && _this.emit('error', _this._error);
- }
- if (err) {
- return _this.emit('error', err);
- }
- _this.cursor = cursor;
- _this.emit('cursor', cursor);
- });
- });
- }
- util.inherits(QueryCursor, Readable);
- /*!
- * Necessary to satisfy the Readable API
- */
- QueryCursor.prototype._read = function() {
- var _this = this;
- _next(this, function(error, doc) {
- if (error) {
- return _this.emit('error', error);
- }
- if (!doc) {
- _this.push(null);
- _this.cursor.close(function(error) {
- if (error) {
- return _this.emit('error', error);
- }
- setTimeout(function() {
- _this.emit('close');
- }, 0);
- });
- return;
- }
- _this.push(doc);
- });
- };
- /**
- * Registers a transform function which subsequently maps documents retrieved
- * via the streams interface or `.next()`
- *
- * ####Example
- *
- * // Map documents returned by `data` events
- * Thing.
- * find({ name: /^hello/ }).
- * cursor().
- * map(function (doc) {
- * doc.foo = "bar";
- * return doc;
- * })
- * on('data', function(doc) { console.log(doc.foo); });
- *
- * // Or map documents returned by `.next()`
- * var cursor = Thing.find({ name: /^hello/ }).
- * cursor().
- * map(function (doc) {
- * doc.foo = "bar";
- * return doc;
- * });
- * cursor.next(function(error, doc) {
- * console.log(doc.foo);
- * });
- *
- * @param {Function} fn
- * @return {QueryCursor}
- * @api public
- * @method map
- */
- QueryCursor.prototype.map = function(fn) {
- this._transforms.push(fn);
- return this;
- };
- /*!
- * Marks this cursor as errored
- */
- QueryCursor.prototype._markError = function(error) {
- this._error = error;
- return this;
- };
- /**
- * Marks this cursor as closed. Will stop streaming and subsequent calls to
- * `next()` will error.
- *
- * @param {Function} callback
- * @return {Promise}
- * @api public
- * @method close
- * @emits close
- * @see MongoDB driver cursor#close http://mongodb.github.io/node-mongodb-native/2.1/api/Cursor.html#close
- */
- QueryCursor.prototype.close = function(callback) {
- return utils.promiseOrCallback(callback, cb => {
- this.cursor.close(error => {
- if (error) {
- cb(error);
- return this.listeners('error').length > 0 && this.emit('error', error);
- }
- this.emit('close');
- cb(null);
- });
- });
- };
- /**
- * Get the next document from this cursor. Will return `null` when there are
- * no documents left.
- *
- * @param {Function} callback
- * @return {Promise}
- * @api public
- * @method next
- */
- QueryCursor.prototype.next = function(callback) {
- return utils.promiseOrCallback(callback, cb => {
- _next(this, function(error, doc) {
- if (error) {
- return cb(error);
- }
- cb(null, doc);
- });
- });
- };
- /**
- * Execute `fn` for every document in the cursor. If `fn` returns a promise,
- * will wait for the promise to resolve before iterating on to the next one.
- * Returns a promise that resolves when done.
- *
- * @param {Function} fn
- * @param {Object} [options]
- * @param {Number} [options.parallel] the number of promises to execute in parallel. Defaults to 1.
- * @param {Function} [callback] executed when all docs have been processed
- * @return {Promise}
- * @api public
- * @method eachAsync
- */
- QueryCursor.prototype.eachAsync = function(fn, opts, callback) {
- var _this = this;
- if (typeof opts === 'function') {
- callback = opts;
- opts = {};
- }
- opts = opts || {};
- return eachAsync(function(cb) { return _next(_this, cb); }, fn, opts, callback);
- };
- /**
- * Adds a [cursor flag](http://mongodb.github.io/node-mongodb-native/2.2/api/Cursor.html#addCursorFlag).
- * Useful for setting the `noCursorTimeout` and `tailable` flags.
- *
- * @param {String} flag
- * @param {Boolean} value
- * @return {AggregationCursor} this
- * @api public
- * @method addCursorFlag
- */
- QueryCursor.prototype.addCursorFlag = function(flag, value) {
- var _this = this;
- _waitForCursor(this, function() {
- _this.cursor.addCursorFlag(flag, value);
- });
- return this;
- };
- /*!
- * Get the next doc from the underlying cursor and mongooseify it
- * (populate, etc.)
- */
- function _next(ctx, cb) {
- var callback = cb;
- if (ctx._transforms.length) {
- callback = function(err, doc) {
- if (err || doc === null) {
- return cb(err, doc);
- }
- cb(err, ctx._transforms.reduce(function(doc, fn) {
- return fn(doc);
- }, doc));
- };
- }
- if (ctx._error) {
- return process.nextTick(function() {
- callback(ctx._error);
- });
- }
- if (ctx.cursor) {
- return ctx.cursor.next(function(error, doc) {
- if (error) {
- return callback(error);
- }
- if (!doc) {
- return callback(null, null);
- }
- var opts = ctx.query._mongooseOptions;
- if (!opts.populate) {
- return opts.lean === true ?
- callback(null, doc) :
- _create(ctx, doc, null, callback);
- }
- var pop = helpers.preparePopulationOptionsMQ(ctx.query,
- ctx.query._mongooseOptions);
- pop.__noPromise = true;
- ctx.query.model.populate(doc, pop, function(err, doc) {
- if (err) {
- return callback(err);
- }
- return opts.lean === true ?
- callback(null, doc) :
- _create(ctx, doc, pop, callback);
- });
- });
- } else {
- ctx.once('cursor', function() {
- _next(ctx, cb);
- });
- }
- }
- /*!
- * ignore
- */
- function _waitForCursor(ctx, cb) {
- if (ctx.cursor) {
- return cb();
- }
- ctx.once('cursor', function() {
- cb();
- });
- }
- /*!
- * Convert a raw doc into a full mongoose doc.
- */
- function _create(ctx, doc, populatedIds, cb) {
- var instance = helpers.createModel(ctx.query.model, doc, ctx.query._fields);
- var opts = populatedIds ?
- { populated: populatedIds } :
- undefined;
- instance.init(doc, opts, function(err) {
- if (err) {
- return cb(err);
- }
- cb(null, instance);
- });
- }
- module.exports = QueryCursor;