deno.land / x / mongoose@6.7.5 / lib / cursor / QueryCursor.js
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'use strict';
const Readable = require('stream').Readable;const promiseOrCallback = require('../helpers/promiseOrCallback');const eachAsync = require('../helpers/cursor/eachAsync');const helpers = require('../queryhelpers');const immediate = require('../helpers/immediate');const util = require('util');
/** * 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 before loading any documents * from MongoDB, and the model's post `find` hooks after loading each document. * * 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) { // set autoDestroy=true because on node 12 it's by default false // gh-10902 need autoDestroy to destroy correctly and emit 'close' event Readable.call(this, { autoDestroy: true, objectMode: true });
this.cursor = null; this.query = query; const _this = this; const model = query.model; this._mongooseOptions = {}; this._transforms = []; this.model = model; this.options = options || {};
model.hooks.execPre('find', query, (err) => { if (err != null) { _this._markError(err); _this.listeners('error').length > 0 && _this.emit('error', err); return; } this._transforms = this._transforms.concat(query._transforms.slice()); if (this.options.transform) { this._transforms.push(options.transform); } // Re: gh-8039, you need to set the `cursor.batchSize` option, top-level // `batchSize` option doesn't work. if (this.options.batchSize) { this.options.cursor = options.cursor || {}; this.options.cursor.batchSize = options.batchSize;
// Max out the number of documents we'll populate in parallel at 5000. this.options._populateBatchSize = Math.min(this.options.batchSize, 5000); } model.collection.find(query._conditions, this.options, (err, cursor) => { if (err != null) { _this._markError(err); _this.listeners('error').length > 0 && _this.emit('error', _this._error); return; }
if (_this._error) { cursor.close(function() {}); _this.listeners('error').length > 0 && _this.emit('error', _this._error); } _this.cursor = cursor; _this.emit('cursor', cursor); }); });}
util.inherits(QueryCursor, Readable);
/** * Necessary to satisfy the Readable API * @method _read * @memberOf QueryCursor * @instance * @api private */
QueryCursor.prototype._read = function() { const _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); } }); 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()` * const 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} * @memberOf QueryCursor * @api public * @method map */
Object.defineProperty(QueryCursor.prototype, 'map', { value: function(fn) { this._transforms.push(fn); return this; }, enumerable: true, configurable: true, writable: true});
/** * Marks this cursor as errored * @method _markError * @memberOf QueryCursor * @instance * @api private */
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 AggregationCursor.close https://mongodb.github.io/node-mongodb-native/4.9/classes/AggregationCursor.html#close */
QueryCursor.prototype.close = function(callback) { return 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); }); }, this.model.events);};
/** * 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 promiseOrCallback(callback, cb => { _next(this, function(error, doc) { if (error) { return cb(error); } cb(null, doc); }); }, this.model.events);};
/** * 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. * * #### Example: * * // Iterate over documents asynchronously * Thing. * find({ name: /^hello/ }). * cursor(). * eachAsync(async function (doc, i) { * doc.foo = doc.bar + i; * await doc.save(); * }) * * @param {Function} fn * @param {Object} [options] * @param {Number} [options.parallel] the number of promises to execute in parallel. Defaults to 1. * @param {Number} [options.batchSize] if set, will call `fn()` with arrays of documents with length at most `batchSize` * @param {Boolean} [options.continueOnError=false] if true, `eachAsync()` iterates through all docs even if `fn` throws an error. If false, `eachAsync()` throws an error immediately if the given function `fn()` throws an error. * @param {Function} [callback] executed when all docs have been processed * @return {Promise} * @api public * @method eachAsync */
QueryCursor.prototype.eachAsync = function(fn, opts, callback) { const _this = this; if (typeof opts === 'function') { callback = opts; opts = {}; } opts = opts || {};
return eachAsync(function(cb) { return _next(_this, cb); }, fn, opts, callback);};
/** * The `options` passed in to the `QueryCursor` constructor. * * @api public * @property options */
QueryCursor.prototype.options;
/** * Adds a [cursor flag](https://mongodb.github.io/node-mongodb-native/4.9/classes/FindCursor.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) { const _this = this; _waitForCursor(this, function() { _this.cursor.addCursorFlag(flag, value); }); return this;};
/*! * ignore */
QueryCursor.prototype.transformNull = function(val) { if (arguments.length === 0) { val = true; } this._mongooseOptions.transformNull = val; return this;};
/*! * ignore */
QueryCursor.prototype._transformForAsyncIterator = function() { if (this._transforms.indexOf(_transformForAsyncIterator) === -1) { this.map(_transformForAsyncIterator); } return this;};
/** * Returns an asyncIterator for use with [`for/await/of` loops](https://thecodebarbarian.com/getting-started-with-async-iterators-in-node-js). * You do not need to call this function explicitly, the JavaScript runtime * will call it for you. * * #### Example: * * // Works without using `cursor()` * for await (const doc of Model.find([{ $sort: { name: 1 } }])) { * console.log(doc.name); * } * * // Can also use `cursor()` * for await (const doc of Model.find([{ $sort: { name: 1 } }]).cursor()) { * console.log(doc.name); * } * * Node.js 10.x supports async iterators natively without any flags. You can * enable async iterators in Node.js 8.x using the [`--harmony_async_iteration` flag](https://github.com/tc39/proposal-async-iteration/issues/117#issuecomment-346695187). * * **Note:** This function is not if `Symbol.asyncIterator` is undefined. If * `Symbol.asyncIterator` is undefined, that means your Node.js version does not * support async iterators. * * @method Symbol.asyncIterator * @memberOf QueryCursor * @instance * @api public */
if (Symbol.asyncIterator != null) { QueryCursor.prototype[Symbol.asyncIterator] = function() { return this.transformNull()._transformForAsyncIterator(); };}
/*! * ignore */
function _transformForAsyncIterator(doc) { return doc == null ? { done: true } : { value: doc, done: false };}
/** * Get the next doc from the underlying cursor and mongooseify it * (populate, etc.) * @param {Any} ctx * @param {Function} cb * @api private */
function _next(ctx, cb) { let callback = cb; if (ctx._transforms.length) { callback = function(err, doc) { if (err || (doc === null && !ctx._mongooseOptions.transformNull)) { return cb(err, doc); } cb(err, ctx._transforms.reduce(function(doc, fn) { return fn.call(ctx, doc); }, doc)); }; }
if (ctx._error) { return immediate(function() { callback(ctx._error); }); }
if (ctx.cursor) { if (ctx.query._mongooseOptions.populate && !ctx._pop) { ctx._pop = helpers.preparePopulationOptionsMQ(ctx.query, ctx.query._mongooseOptions); ctx._pop.__noPromise = true; } if (ctx.query._mongooseOptions.populate && ctx.options._populateBatchSize > 1) { if (ctx._batchDocs && ctx._batchDocs.length) { // Return a cached populated doc return _nextDoc(ctx, ctx._batchDocs.shift(), ctx._pop, callback); } else if (ctx._batchExhausted) { // Internal cursor reported no more docs. Act the same here return callback(null, null); } else { // Request as many docs as batchSize, to populate them also in batch ctx._batchDocs = []; return ctx.cursor.next(_onNext.bind({ ctx, callback })); } } else { return ctx.cursor.next(function(error, doc) { if (error) { return callback(error); } if (!doc) { return callback(null, null); }
if (!ctx.query._mongooseOptions.populate) { return _nextDoc(ctx, doc, null, callback); }
ctx.query.model.populate(doc, ctx._pop, function(err, doc) { if (err) { return callback(err); } return _nextDoc(ctx, doc, ctx._pop, callback); }); }); } } else { ctx.once('error', cb);
ctx.once('cursor', function(cursor) { ctx.removeListener('error', cb); if (cursor == null) { return; } _next(ctx, cb); }); }}
/*! * ignore */
function _onNext(error, doc) { if (error) { return this.callback(error); } if (!doc) { this.ctx._batchExhausted = true; return _populateBatch.call(this); }
this.ctx._batchDocs.push(doc);
if (this.ctx._batchDocs.length < this.ctx.options._populateBatchSize) { // If both `batchSize` and `_populateBatchSize` are huge, calling `next()` repeatedly may // cause a stack overflow. So make sure we clear the stack regularly. if (this.ctx._batchDocs.length > 0 && this.ctx._batchDocs.length % 1000 === 0) { return immediate(() => this.ctx.cursor.next(_onNext.bind(this))); } this.ctx.cursor.next(_onNext.bind(this)); } else { _populateBatch.call(this); }}
/*! * ignore */
function _populateBatch() { if (!this.ctx._batchDocs.length) { return this.callback(null, null); } const _this = this; this.ctx.query.model.populate(this.ctx._batchDocs, this.ctx._pop, function(err) { if (err) { return _this.callback(err); }
_nextDoc(_this.ctx, _this.ctx._batchDocs.shift(), _this.ctx._pop, _this.callback); });}
/*! * ignore */
function _nextDoc(ctx, doc, pop, callback) { if (ctx.query._mongooseOptions.lean) { return ctx.model.hooks.execPost('find', ctx.query, [[doc]], err => { if (err != null) { return callback(err); } callback(null, doc); }); }
const { model, _fields, _userProvidedFields, options } = ctx.query; helpers.createModelAndInit(model, doc, _fields, _userProvidedFields, options, pop, (err, doc) => { if (err != null) { return callback(err); } ctx.model.hooks.execPost('find', ctx.query, [[doc]], err => { if (err != null) { return callback(err); } callback(null, doc); }); });}
/*! * ignore */
function _waitForCursor(ctx, cb) { if (ctx.cursor) { return cb(); } ctx.once('cursor', function(cursor) { if (cursor == null) { return; } cb(); });}
module.exports = QueryCursor;
mongoose
Version Info
a year ago
