https://github.com/Automattic/mongoose
Tip revision: f581e1ebe958f29b3cc13d70ebe8705feaf29ca3 authored by Valeri Karpov on 03 August 2022, 19:55:49 UTC
chore: release 6.5.1
chore: release 6.5.1
Tip revision: f581e1e
aggregate.js
'use strict';
/*!
* Module dependencies
*/
const AggregationCursor = require('./cursor/AggregationCursor');
const Query = require('./query');
const { applyGlobalMaxTimeMS, applyGlobalDiskUse } = require('./helpers/query/applyGlobalOption');
const getConstructorName = require('./helpers/getConstructorName');
const prepareDiscriminatorPipeline = require('./helpers/aggregate/prepareDiscriminatorPipeline');
const promiseOrCallback = require('./helpers/promiseOrCallback');
const stringifyFunctionOperators = require('./helpers/aggregate/stringifyFunctionOperators');
const utils = require('./utils');
const read = Query.prototype.read;
const readConcern = Query.prototype.readConcern;
const validRedactStringValues = new Set(['$$DESCEND', '$$PRUNE', '$$KEEP']);
/**
* Aggregate constructor used for building aggregation pipelines. Do not
* instantiate this class directly, use [Model.aggregate()](/docs/api.html#model_Model-aggregate) instead.
*
* #### Example:
*
* const aggregate = Model.aggregate([
* { $project: { a: 1, b: 1 } },
* { $skip: 5 }
* ]);
*
* Model.
* aggregate([{ $match: { age: { $gte: 21 }}}]).
* unwind('tags').
* exec(callback);
*
* #### Note:
*
* - The documents returned are plain javascript objects, not mongoose documents (since any shape of document can be returned).
* - Mongoose does **not** cast pipeline stages. The below will **not** work unless `_id` is a string in the database
*
* new Aggregate([{ $match: { _id: '00000000000000000000000a' } }]);
* // Do this instead to cast to an ObjectId
* new Aggregate([{ $match: { _id: new mongoose.Types.ObjectId('00000000000000000000000a') } }]);
*
* @see MongoDB https://docs.mongodb.org/manual/applications/aggregation/
* @see driver https://mongodb.github.com/node-mongodb-native/api-generated/collection.html#aggregate
* @param {Array} [pipeline] aggregation pipeline as an array of objects
* @param {Model} [model] the model to use with this aggregate.
* @api public
*/
function Aggregate(pipeline, model) {
this._pipeline = [];
this._model = model;
this.options = {};
if (arguments.length === 1 && Array.isArray(pipeline)) {
this.append.apply(this, pipeline);
}
}
/**
* Contains options passed down to the [aggregate command](https://docs.mongodb.com/manual/reference/command/aggregate/).
* Supported options are:
*
* - [`allowDiskUse`](./api.html#aggregate_Aggregate-allowDiskUse)
* - `bypassDocumentValidation`
* - [`collation`](./api.html#aggregate_Aggregate-collation)
* - `comment`
* - [`cursor`](./api.html#aggregate_Aggregate-cursor)
* - [`explain`](./api.html#aggregate_Aggregate-explain)
* - `fieldsAsRaw`
* - `hint`
* - `let`
* - `maxTimeMS`
* - `raw`
* - `readConcern`
* - `readPreference`
* - [`session`](./api.html#aggregate_Aggregate-session)
* - `writeConcern`
*
* @property options
* @memberOf Aggregate
* @api public
*/
Aggregate.prototype.options;
/**
* Get/set the model that this aggregation will execute on.
*
* #### Example:
*
* const aggregate = MyModel.aggregate([{ $match: { answer: 42 } }]);
* aggregate.model() === MyModel; // true
*
* // Change the model. There's rarely any reason to do this.
* aggregate.model(SomeOtherModel);
* aggregate.model() === SomeOtherModel; // true
*
* @param {Model} [model] Set the model associated with this aggregate. If not provided, returns the already stored model.
* @return {Model}
* @api public
*/
Aggregate.prototype.model = function(model) {
if (arguments.length === 0) {
return this._model;
}
this._model = model;
if (model.schema != null) {
if (this.options.readPreference == null &&
model.schema.options.read != null) {
this.options.readPreference = model.schema.options.read;
}
if (this.options.collation == null &&
model.schema.options.collation != null) {
this.options.collation = model.schema.options.collation;
}
}
return model;
};
/**
* Appends new operators to this aggregate pipeline
*
* #### Examples:
*
* aggregate.append({ $project: { field: 1 }}, { $limit: 2 });
*
* // or pass an array
* const pipeline = [{ $match: { daw: 'Logic Audio X' }} ];
* aggregate.append(pipeline);
*
* @param {...Object|Object[]} ops operator(s) to append. Can either be a spread of objects or a single parameter of a object array.
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.append = function() {
const args = (arguments.length === 1 && Array.isArray(arguments[0]))
? arguments[0]
: [...arguments];
if (!args.every(isOperator)) {
throw new Error('Arguments must be aggregate pipeline operators');
}
this._pipeline = this._pipeline.concat(args);
return this;
};
/**
* Appends a new $addFields operator to this aggregate pipeline.
* Requires MongoDB v3.4+ to work
*
* #### Examples:
*
* // adding new fields based on existing fields
* aggregate.addFields({
* newField: '$b.nested'
* , plusTen: { $add: ['$val', 10]}
* , sub: {
* name: '$a'
* }
* })
*
* // etc
* aggregate.addFields({ salary_k: { $divide: [ "$salary", 1000 ] } });
*
* @param {Object} arg field specification
* @see $addFields https://docs.mongodb.com/manual/reference/operator/aggregation/addFields/
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.addFields = function(arg) {
if (typeof arg !== 'object' || arg === null || Array.isArray(arg)) {
throw new Error('Invalid addFields() argument. Must be an object');
}
return this.append({ $addFields: Object.assign({}, arg) });
};
/**
* Appends a new $project operator to this aggregate pipeline.
*
* Mongoose query [selection syntax](#query_Query-select) is also supported.
*
* #### Examples:
*
* // include a, include b, exclude _id
* aggregate.project("a b -_id");
*
* // or you may use object notation, useful when
* // you have keys already prefixed with a "-"
* aggregate.project({a: 1, b: 1, _id: 0});
*
* // reshaping documents
* aggregate.project({
* newField: '$b.nested'
* , plusTen: { $add: ['$val', 10]}
* , sub: {
* name: '$a'
* }
* })
*
* // etc
* aggregate.project({ salary_k: { $divide: [ "$salary", 1000 ] } });
*
* @param {Object|String} arg field specification
* @see projection https://docs.mongodb.org/manual/reference/aggregation/project/
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.project = function(arg) {
const fields = {};
if (typeof arg === 'object' && !Array.isArray(arg)) {
Object.keys(arg).forEach(function(field) {
fields[field] = arg[field];
});
} else if (arguments.length === 1 && typeof arg === 'string') {
arg.split(/\s+/).forEach(function(field) {
if (!field) {
return;
}
const include = field[0] === '-' ? 0 : 1;
if (include === 0) {
field = field.substring(1);
}
fields[field] = include;
});
} else {
throw new Error('Invalid project() argument. Must be string or object');
}
return this.append({ $project: fields });
};
/**
* Appends a new custom $group operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.group({ _id: "$department" });
*
* @see $group https://docs.mongodb.org/manual/reference/aggregation/group/
* @method group
* @memberOf Aggregate
* @instance
* @param {Object} arg $group operator contents
* @return {Aggregate}
* @api public
*/
/**
* Appends a new custom $match operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.match({ department: { $in: [ "sales", "engineering" ] } });
*
* @see $match https://docs.mongodb.org/manual/reference/aggregation/match/
* @method match
* @memberOf Aggregate
* @instance
* @param {Object} arg $match operator contents
* @return {Aggregate}
* @api public
*/
/**
* Appends a new $skip operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.skip(10);
*
* @see $skip https://docs.mongodb.org/manual/reference/aggregation/skip/
* @method skip
* @memberOf Aggregate
* @instance
* @param {Number} num number of records to skip before next stage
* @return {Aggregate}
* @api public
*/
/**
* Appends a new $limit operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.limit(10);
*
* @see $limit https://docs.mongodb.org/manual/reference/aggregation/limit/
* @method limit
* @memberOf Aggregate
* @instance
* @param {Number} num maximum number of records to pass to the next stage
* @return {Aggregate}
* @api public
*/
/**
* Appends a new $geoNear operator to this aggregate pipeline.
*
* #### Note:
*
* **MUST** be used as the first operator in the pipeline.
*
* #### Examples:
*
* aggregate.near({
* near: [40.724, -73.997],
* distanceField: "dist.calculated", // required
* maxDistance: 0.008,
* query: { type: "public" },
* includeLocs: "dist.location",
* uniqueDocs: true,
* num: 5
* });
*
* @see $geoNear https://docs.mongodb.org/manual/reference/aggregation/geoNear/
* @method near
* @memberOf Aggregate
* @instance
* @param {Object} arg
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.near = function(arg) {
const op = {};
op.$geoNear = arg;
return this.append(op);
};
/*!
* define methods
*/
'group match skip limit out'.split(' ').forEach(function($operator) {
Aggregate.prototype[$operator] = function(arg) {
const op = {};
op['$' + $operator] = arg;
return this.append(op);
};
});
/**
* Appends new custom $unwind operator(s) to this aggregate pipeline.
*
* Note that the `$unwind` operator requires the path name to start with '$'.
* Mongoose will prepend '$' if the specified field doesn't start '$'.
*
* #### Examples:
*
* aggregate.unwind("tags");
* aggregate.unwind("a", "b", "c");
* aggregate.unwind({ path: '$tags', preserveNullAndEmptyArrays: true });
*
* @see $unwind https://docs.mongodb.org/manual/reference/aggregation/unwind/
* @param {String|Object|String[]|Object[]} fields the field(s) to unwind, either as field names or as [objects with options](https://docs.mongodb.com/manual/reference/operator/aggregation/unwind/#document-operand-with-options). If passing a string, prefixing the field name with '$' is optional. If passing an object, `path` must start with '$'.
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.unwind = function() {
const args = [...arguments];
const res = [];
for (const arg of args) {
if (arg && typeof arg === 'object') {
res.push({ $unwind: arg });
} else if (typeof arg === 'string') {
res.push({
$unwind: (arg[0] === '$') ? arg : '$' + arg
});
} else {
throw new Error('Invalid arg "' + arg + '" to unwind(), ' +
'must be string or object');
}
}
return this.append.apply(this, res);
};
/**
* Appends a new $replaceRoot operator to this aggregate pipeline.
*
* Note that the `$replaceRoot` operator requires field strings to start with '$'.
* If you are passing in a string Mongoose will prepend '$' if the specified field doesn't start '$'.
* If you are passing in an object the strings in your expression will not be altered.
*
* #### Examples:
*
* aggregate.replaceRoot("user");
*
* aggregate.replaceRoot({ x: { $concat: ['$this', '$that'] } });
*
* @see $replaceRoot https://docs.mongodb.org/manual/reference/operator/aggregation/replaceRoot
* @param {String|Object} newRoot the field or document which will become the new root document
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.replaceRoot = function(newRoot) {
let ret;
if (typeof newRoot === 'string') {
ret = newRoot.startsWith('$') ? newRoot : '$' + newRoot;
} else {
ret = newRoot;
}
return this.append({
$replaceRoot: {
newRoot: ret
}
});
};
/**
* Appends a new $count operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.count("userCount");
*
* @see $count https://docs.mongodb.org/manual/reference/operator/aggregation/count
* @param {String} fieldName The name of the output field which has the count as its value. It must be a non-empty string, must not start with $ and must not contain the . character.
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.count = function(fieldName) {
return this.append({ $count: fieldName });
};
/**
* Appends a new $sortByCount operator to this aggregate pipeline. Accepts either a string field name
* or a pipeline object.
*
* Note that the `$sortByCount` operator requires the new root to start with '$'.
* Mongoose will prepend '$' if the specified field name doesn't start with '$'.
*
* #### Examples:
*
* aggregate.sortByCount('users');
* aggregate.sortByCount({ $mergeObjects: [ "$employee", "$business" ] })
*
* @see $sortByCount https://docs.mongodb.com/manual/reference/operator/aggregation/sortByCount/
* @param {Object|String} arg
* @return {Aggregate} this
* @api public
*/
Aggregate.prototype.sortByCount = function(arg) {
if (arg && typeof arg === 'object') {
return this.append({ $sortByCount: arg });
} else if (typeof arg === 'string') {
return this.append({
$sortByCount: (arg[0] === '$') ? arg : '$' + arg
});
} else {
throw new TypeError('Invalid arg "' + arg + '" to sortByCount(), ' +
'must be string or object');
}
};
/**
* Appends new custom $lookup operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.lookup({ from: 'users', localField: 'userId', foreignField: '_id', as: 'users' });
*
* @see $lookup https://docs.mongodb.org/manual/reference/operator/aggregation/lookup/#pipe._S_lookup
* @param {Object} options to $lookup as described in the above link
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.lookup = function(options) {
return this.append({ $lookup: options });
};
/**
* Appends new custom $graphLookup operator(s) to this aggregate pipeline, performing a recursive search on a collection.
*
* Note that graphLookup can only consume at most 100MB of memory, and does not allow disk use even if `{ allowDiskUse: true }` is specified.
*
* #### Examples:
*
* // Suppose we have a collection of courses, where a document might look like `{ _id: 0, name: 'Calculus', prerequisite: 'Trigonometry'}` and `{ _id: 0, name: 'Trigonometry', prerequisite: 'Algebra' }`
* aggregate.graphLookup({ from: 'courses', startWith: '$prerequisite', connectFromField: 'prerequisite', connectToField: 'name', as: 'prerequisites', maxDepth: 3 }) // this will recursively search the 'courses' collection up to 3 prerequisites
*
* @see $graphLookup https://docs.mongodb.com/manual/reference/operator/aggregation/graphLookup/#pipe._S_graphLookup
* @param {Object} options to $graphLookup as described in the above link
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.graphLookup = function(options) {
const cloneOptions = {};
if (options) {
if (!utils.isObject(options)) {
throw new TypeError('Invalid graphLookup() argument. Must be an object.');
}
utils.mergeClone(cloneOptions, options);
const startWith = cloneOptions.startWith;
if (startWith && typeof startWith === 'string') {
cloneOptions.startWith = cloneOptions.startWith.startsWith('$') ?
cloneOptions.startWith :
'$' + cloneOptions.startWith;
}
}
return this.append({ $graphLookup: cloneOptions });
};
/**
* Appends new custom $sample operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.sample(3); // Add a pipeline that picks 3 random documents
*
* @see $sample https://docs.mongodb.org/manual/reference/operator/aggregation/sample/#pipe._S_sample
* @param {Number} size number of random documents to pick
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.sample = function(size) {
return this.append({ $sample: { size: size } });
};
/**
* Appends a new $sort operator to this aggregate pipeline.
*
* If an object is passed, values allowed are `asc`, `desc`, `ascending`, `descending`, `1`, and `-1`.
*
* If a string is passed, it must be a space delimited list of path names. The sort order of each path is ascending unless the path name is prefixed with `-` which will be treated as descending.
*
* #### Examples:
*
* // these are equivalent
* aggregate.sort({ field: 'asc', test: -1 });
* aggregate.sort('field -test');
*
* @see $sort https://docs.mongodb.org/manual/reference/aggregation/sort/
* @param {Object|String} arg
* @return {Aggregate} this
* @api public
*/
Aggregate.prototype.sort = function(arg) {
// TODO refactor to reuse the query builder logic
const sort = {};
if (getConstructorName(arg) === 'Object') {
const desc = ['desc', 'descending', -1];
Object.keys(arg).forEach(function(field) {
// If sorting by text score, skip coercing into 1/-1
if (arg[field] instanceof Object && arg[field].$meta) {
sort[field] = arg[field];
return;
}
sort[field] = desc.indexOf(arg[field]) === -1 ? 1 : -1;
});
} else if (arguments.length === 1 && typeof arg === 'string') {
arg.split(/\s+/).forEach(function(field) {
if (!field) {
return;
}
const ascend = field[0] === '-' ? -1 : 1;
if (ascend === -1) {
field = field.substring(1);
}
sort[field] = ascend;
});
} else {
throw new TypeError('Invalid sort() argument. Must be a string or object.');
}
return this.append({ $sort: sort });
};
/**
* Appends new $unionWith operator to this aggregate pipeline.
*
* #### Examples:
*
* aggregate.unionWith({ coll: 'users', pipeline: [ { $match: { _id: 1 } } ] });
*
* @see $unionWith https://docs.mongodb.com/manual/reference/operator/aggregation/unionWith
* @param {Object} options to $unionWith query as described in the above link
* @return {Aggregate}
* @api public
*/
Aggregate.prototype.unionWith = function(options) {
return this.append({ $unionWith: options });
};
/**
* Sets the readPreference option for the aggregation query.
*
* #### Example:
*
* await Model.aggregate(pipeline).read('primaryPreferred');
*
* @param {String|ReadPreference} pref one of the listed preference options or their aliases
* @param {Array} [tags] optional tags for this query. DEPRECATED
* @return {Aggregate} this
* @api public
* @see mongodb https://docs.mongodb.org/manual/applications/replication/#read-preference
* @see driver https://mongodb.github.com/node-mongodb-native/driver-articles/anintroductionto1_1and2_2.html#read-preferences
*/
Aggregate.prototype.read = function(pref, tags) {
read.call(this, pref, tags);
return this;
};
/**
* Sets the readConcern level for the aggregation query.
*
* #### Example:
*
* await Model.aggregate(pipeline).readConcern('majority');
*
* @param {String} level one of the listed read concern level or their aliases
* @see mongodb https://docs.mongodb.com/manual/reference/read-concern/
* @return {Aggregate} this
* @api public
*/
Aggregate.prototype.readConcern = function(level) {
readConcern.call(this, level);
return this;
};
/**
* Appends a new $redact operator to this aggregate pipeline.
*
* If 3 arguments are supplied, Mongoose will wrap them with if-then-else of $cond operator respectively
* If `thenExpr` or `elseExpr` is string, make sure it starts with $$, like `$$DESCEND`, `$$PRUNE` or `$$KEEP`.
*
* #### Example:
*
* await Model.aggregate(pipeline).redact({
* $cond: {
* if: { $eq: [ '$level', 5 ] },
* then: '$$PRUNE',
* else: '$$DESCEND'
* }
* });
*
* // $redact often comes with $cond operator, you can also use the following syntax provided by mongoose
* await Model.aggregate(pipeline).redact({ $eq: [ '$level', 5 ] }, '$$PRUNE', '$$DESCEND');
*
* @param {Object} expression redact options or conditional expression
* @param {String|Object} [thenExpr] true case for the condition
* @param {String|Object} [elseExpr] false case for the condition
* @return {Aggregate} this
* @see $redact https://docs.mongodb.com/manual/reference/operator/aggregation/redact/
* @api public
*/
Aggregate.prototype.redact = function(expression, thenExpr, elseExpr) {
if (arguments.length === 3) {
if ((typeof thenExpr === 'string' && !validRedactStringValues.has(thenExpr)) ||
(typeof elseExpr === 'string' && !validRedactStringValues.has(elseExpr))) {
throw new Error('If thenExpr or elseExpr is string, it must be either $$DESCEND, $$PRUNE or $$KEEP');
}
expression = {
$cond: {
if: expression,
then: thenExpr,
else: elseExpr
}
};
} else if (arguments.length !== 1) {
throw new TypeError('Invalid arguments');
}
return this.append({ $redact: expression });
};
/**
* Execute the aggregation with explain
*
* #### Example:
*
* Model.aggregate(..).explain(callback)
*
* @param {String} [verbosity]
* @param {Function} [callback] The callback function to call, if not specified, will return a Promise instead.
* @return {Promise} Returns a promise if no "callback" is given
*/
Aggregate.prototype.explain = function(verbosity, callback) {
const model = this._model;
if (typeof verbosity === 'function') {
callback = verbosity;
verbosity = null;
}
return promiseOrCallback(callback, cb => {
if (!this._pipeline.length) {
const err = new Error('Aggregate has empty pipeline');
return cb(err);
}
prepareDiscriminatorPipeline(this._pipeline, this._model.schema);
model.hooks.execPre('aggregate', this, error => {
if (error) {
const _opts = { error: error };
return model.hooks.execPost('aggregate', this, [null], _opts, error => {
cb(error);
});
}
model.collection.aggregate(this._pipeline, this.options, (error, cursor) => {
if (error != null) {
const _opts = { error: error };
return model.hooks.execPost('aggregate', this, [null], _opts, error => {
cb(error);
});
}
if (verbosity != null) {
cursor.explain(verbosity, (error, result) => {
const _opts = { error: error };
return model.hooks.execPost('aggregate', this, [result], _opts, error => {
if (error) {
return cb(error);
}
return cb(null, result);
});
});
} else {
cursor.explain((error, result) => {
const _opts = { error: error };
return model.hooks.execPost('aggregate', this, [result], _opts, error => {
if (error) {
return cb(error);
}
return cb(null, result);
});
});
}
});
});
}, model.events);
};
/**
* Sets the allowDiskUse option for the aggregation query (ignored for < 2.6.0)
*
* #### Example:
*
* await Model.aggregate([{ $match: { foo: 'bar' } }]).allowDiskUse(true);
*
* @param {Boolean} value Should tell server it can use hard drive to store data during aggregation.
* @return {Aggregate} this
* @see mongodb https://docs.mongodb.org/manual/reference/command/aggregate/
*/
Aggregate.prototype.allowDiskUse = function(value) {
this.options.allowDiskUse = value;
return this;
};
/**
* Sets the hint option for the aggregation query (ignored for < 3.6.0)
*
* #### Example:
*
* Model.aggregate(..).hint({ qty: 1, category: 1 }).exec(callback)
*
* @param {Object|String} value a hint object or the index name
* @return {Aggregate} this
* @see mongodb https://docs.mongodb.org/manual/reference/command/aggregate/
*/
Aggregate.prototype.hint = function(value) {
this.options.hint = value;
return this;
};
/**
* Sets the session for this aggregation. Useful for [transactions](/docs/transactions.html).
*
* #### Example:
*
* const session = await Model.startSession();
* await Model.aggregate(..).session(session);
*
* @param {ClientSession} session
* @return {Aggregate} this
* @see mongodb https://docs.mongodb.org/manual/reference/command/aggregate/
*/
Aggregate.prototype.session = function(session) {
if (session == null) {
delete this.options.session;
} else {
this.options.session = session;
}
return this;
};
/**
* Lets you set arbitrary options, for middleware or plugins.
*
* #### Example:
*
* const agg = Model.aggregate(..).option({ allowDiskUse: true }); // Set the `allowDiskUse` option
* agg.options; // `{ allowDiskUse: true }`
*
* @param {Object} options keys to merge into current options
* @param {Number} [options.maxTimeMS] number limits the time this aggregation will run, see [MongoDB docs on `maxTimeMS`](https://docs.mongodb.com/manual/reference/operator/meta/maxTimeMS/)
* @param {Boolean} [options.allowDiskUse] boolean if true, the MongoDB server will use the hard drive to store data during this aggregation
* @param {Object} [options.collation] object see [`Aggregate.prototype.collation()`](./docs/api.html#aggregate_Aggregate-collation)
* @param {ClientSession} [options.session] ClientSession see [`Aggregate.prototype.session()`](./docs/api.html#aggregate_Aggregate-session)
* @see mongodb https://docs.mongodb.org/manual/reference/command/aggregate/
* @return {Aggregate} this
* @api public
*/
Aggregate.prototype.option = function(value) {
for (const key in value) {
this.options[key] = value[key];
}
return this;
};
/**
* Sets the `cursor` option and executes this aggregation, returning an aggregation cursor.
* Cursors are useful if you want to process the results of the aggregation one-at-a-time
* because the aggregation result is too big to fit into memory.
*
* #### Example:
*
* const cursor = Model.aggregate(..).cursor({ batchSize: 1000 });
* cursor.eachAsync(function(doc, i) {
* // use doc
* });
*
* @param {Object} options
* @param {Number} [options.batchSize] set the cursor batch size
* @param {Boolean} [options.useMongooseAggCursor] use experimental mongoose-specific aggregation cursor (for `eachAsync()` and other query cursor semantics)
* @return {AggregationCursor} cursor representing this aggregation
* @api public
* @see mongodb https://mongodb.github.io/node-mongodb-native/2.0/api/AggregationCursor.html
*/
Aggregate.prototype.cursor = function(options) {
this.options.cursor = options || {};
return new AggregationCursor(this); // return this;
};
/**
* Adds a collation
*
* #### Example:
*
* const res = await Model.aggregate(pipeline).collation({ locale: 'en_US', strength: 1 });
*
* @param {Object} collation options
* @return {Aggregate} this
* @api public
* @see mongodb https://mongodb.github.io/node-mongodb-native/2.2/api/Collection.html#aggregate
*/
Aggregate.prototype.collation = function(collation) {
this.options.collation = collation;
return this;
};
/**
* Combines multiple aggregation pipelines.
*
* #### Example:
*
* const res = await Model.aggregate().facet({
* books: [{ groupBy: '$author' }],
* price: [{ $bucketAuto: { groupBy: '$price', buckets: 2 } }]
* });
*
* // Output: { books: [...], price: [{...}, {...}] }
*
* @param {Object} facet options
* @return {Aggregate} this
* @see $facet https://docs.mongodb.com/v3.4/reference/operator/aggregation/facet/
* @api public
*/
Aggregate.prototype.facet = function(options) {
return this.append({ $facet: options });
};
/**
* Helper for [Atlas Text Search](https://docs.atlas.mongodb.com/reference/atlas-search/tutorial/)'s
* `$search` stage.
*
* #### Example:
*
* const res = await Model.aggregate().
* search({
* text: {
* query: 'baseball',
* path: 'plot'
* }
* });
*
* // Output: [{ plot: '...', title: '...' }]
*
* @param {Object} $search options
* @return {Aggregate} this
* @see $search https://docs.atlas.mongodb.com/reference/atlas-search/tutorial/
* @api public
*/
Aggregate.prototype.search = function(options) {
return this.append({ $search: options });
};
/**
* Returns the current pipeline
*
* #### Example:
*
* MyModel.aggregate().match({ test: 1 }).pipeline(); // [{ $match: { test: 1 } }]
*
* @return {Array} The current pipeline similar to the operation that will be executed
* @api public
*/
Aggregate.prototype.pipeline = function() {
return this._pipeline;
};
/**
* Executes the aggregate pipeline on the currently bound Model.
*
* #### Example:
*
* aggregate.exec(callback);
*
* // Because a promise is returned, the `callback` is optional.
* const result = await aggregate.exec();
*
* @param {Function} [callback]
* @return {Promise} Returns a Promise if no "callback" is given.
* @api public
*/
Aggregate.prototype.exec = function(callback) {
if (!this._model) {
throw new Error('Aggregate not bound to any Model');
}
const model = this._model;
const collection = this._model.collection;
applyGlobalMaxTimeMS(this.options, model);
applyGlobalDiskUse(this.options, model);
if (this.options && this.options.cursor) {
return new AggregationCursor(this);
}
return promiseOrCallback(callback, cb => {
prepareDiscriminatorPipeline(this._pipeline, this._model.schema);
stringifyFunctionOperators(this._pipeline);
model.hooks.execPre('aggregate', this, error => {
if (error) {
const _opts = { error: error };
return model.hooks.execPost('aggregate', this, [null], _opts, error => {
cb(error);
});
}
if (!this._pipeline.length) {
return cb(new Error('Aggregate has empty pipeline'));
}
const options = utils.clone(this.options || {});
collection.aggregate(this._pipeline, options, (err, cursor) => {
if (err != null) {
return cb(err);
}
cursor.toArray((error, result) => {
const _opts = { error: error };
model.hooks.execPost('aggregate', this, [result], _opts, (error, result) => {
if (error) {
return cb(error);
}
cb(null, result);
});
});
});
});
}, model.events);
};
/**
* Provides a Promise-like `then` function, which will call `.exec` without a callback
* Compatible with `await`.
*
* #### Example:
*
* Model.aggregate(..).then(successCallback, errorCallback);
*
* @param {Function} [resolve] successCallback
* @param {Function} [reject] errorCallback
* @return {Promise}
*/
Aggregate.prototype.then = function(resolve, reject) {
return this.exec().then(resolve, reject);
};
/**
* Executes the query returning a `Promise` which will be
* resolved with either the doc(s) or rejected with the error.
* Like [`.then()`](#query_Query-then), but only takes a rejection handler.
* Compatible with `await`.
*
* @param {Function} [reject]
* @return {Promise}
* @api public
*/
Aggregate.prototype.catch = function(reject) {
return this.exec().then(null, reject);
};
/**
* 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:
*
* const agg = Model.aggregate([{ $match: { age: { $gte: 25 } } }]);
* for await (const doc of agg) {
* console.log(doc.name);
* }
*
* Node.js 10.x supports async iterators natively without any flags. You can
* enable async iterators in Node.js 8.x using the [`--harmony_async_iteration` flag](https://github.com/tc39/proposal-async-iteration/issues/117#issuecomment-346695187).
*
* **Note:** This function is not set if `Symbol.asyncIterator` is undefined. If
* `Symbol.asyncIterator` is undefined, that means your Node.js version does not
* support async iterators.
*
* @method Symbol.asyncIterator
* @memberOf Aggregate
* @instance
* @api public
*/
if (Symbol.asyncIterator != null) {
Aggregate.prototype[Symbol.asyncIterator] = function() {
return this.cursor({ useMongooseAggCursor: true }).
transformNull().
_transformForAsyncIterator();
};
}
/*!
* Helpers
*/
/**
* Checks whether an object is likely a pipeline operator
*
* @param {Object} obj object to check
* @return {Boolean}
* @api private
*/
function isOperator(obj) {
if (typeof obj !== 'object' || obj === null) {
return false;
}
const k = Object.keys(obj);
return k.length === 1 && k[0][0] === '$';
}
/*!
* Adds the appropriate `$match` pipeline step to the top of an aggregate's
* pipeline, should it's model is a non-root discriminator type. This is
* analogous to the `prepareDiscriminatorCriteria` function in `lib/query.js`.
*
* @param {Aggregate} aggregate Aggregate to prepare
*/
Aggregate._prepareDiscriminatorPipeline = prepareDiscriminatorPipeline;
/*!
* Exports
*/
module.exports = Aggregate;