聚合¶

Aggregate()¶

参数

[pipeline] «Array» aggregation pipeline as an array of objects

Aggregate constructor used for building aggregation pipelines. Do not instantiate this class directly, use [Model.aggregate() instead.

示例

const aggregate = Model.aggregate([
  { $project: { a: 1, b: 1 } },
  { $skip: 5 }
]);

Model.
  aggregate({ $match: { age: { $gte: 21 }}}).
  unwind('tags').
  exec(callback);

注释

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: mongoose.Types.ObjectId('00000000000000000000000a') } }]);

Aggregate.prototype.model()¶

参数

model «Model» the model to which the aggregate is to be bound

返回

Binds this aggregate to a model.

Aggregate.prototype.append()¶

参数

ops «Object» operator(s) to append

返回

Appends new operators to this aggregate pipeline

示例

aggregate.append({ $project: { field: 1 }}, { $limit: 2 });

var pipeline = [{ $match: { daw: 'Logic Audio X' }} ];
aggregate.append(pipeline);

Aggregate.prototype.addFields()¶

参数

arg «Object» field specification

返回

Appends a new $addFields operator to this aggregate pipeline. Requires MongoDB v3.4+ to work

示例

aggregate.addFields({
    newField: '$b.nested'
  , plusTen: { $add: ['$val', 10]}
  , sub: {
       name: '$a'
    }
})

aggregate.addFields({ salary_k: { $divide: [ "$salary", 1000 ] } });

Aggregate.prototype.project()¶

参数

arg «Object,String» field specification

返回

Appends a new $project operator to this aggregate pipeline.

Mongoose query [selection syntax is also supported.

示例

aggregate.project("a b -_id");

aggregate.project({a: 1, b: 1, _id: 0});

aggregate.project({
    newField: '$b.nested'
  , plusTen: { $add: ['$val', 10]}
  , sub: {
       name: '$a'
    }
})

aggregate.project({ salary_k: { $divide: [ "$salary", 1000 ] } });

Aggregate.prototype.group()¶

参数

arg «Object» $group operator contents

返回

Appends a new custom $group operator to this aggregate pipeline.

示例

aggregate.group({ _id: "$department" });

Aggregate.prototype.match()¶

参数

arg «Object» $match operator contents

返回

Appends a new custom $match operator to this aggregate pipeline.

示例

aggregate.match({ department: { $in: [ "sales", "engineering" ] } });

Aggregate.prototype.skip()¶

参数

num «Number» number of records to skip before next stage

返回

Appends a new $skip operator to this aggregate pipeline.

示例

aggregate.skip(10);

Aggregate.prototype.limit()¶

参数

num «Number» maximum number of records to pass to the next stage

返回

Appends a new $limit operator to this aggregate pipeline.

示例

aggregate.limit(10);

Aggregate.prototype.near()¶

参数

返回

Appends a new $geoNear operator to this aggregate pipeline.

注释

MUST be used as the first operator in the pipeline.

示例

aggregate.near({
  near: [40.724, -73.997],
  distanceField: "dist.calculated",
  maxDistance: 0.008,
  query: { type: "public" },
  includeLocs: "dist.location",
  uniqueDocs: true,
  num: 5
});

Aggregate.prototype.unwind()¶

参数

fields «String» the field(s) to unwind

返回

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 '$' if the specified field doesn't start '$'.

示例

aggregate.unwind("tags");
aggregate.unwind("a", "b", "c");

Aggregate.prototype.lookup()¶

参数

options «Object» to $lookup as described in the above link

返回

Appends new custom $lookup operator(s) to this aggregate pipeline.

示例

aggregate.lookup({ from: 'users', localField: 'userId', foreignField: '_id', as: 'users' });

Aggregate.prototype.graphLookup()¶

参数

options «Object» to $graphLookup as described in the above link

返回

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.

示例

 aggregate.graphLookup({ from: 'courses', startWith: '$prerequisite', connectFromField: 'prerequisite', connectToField: 'name', as: 'prerequisites', maxDepth: 3 })

Aggregate.prototype.sample()¶

参数

size «Number» number of random documents to pick

返回

Appepnds new custom $sample operator(s) to this aggregate pipeline.

示例

aggregate.sample(3);

Aggregate.prototype.sort()¶

参数

返回

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.

示例

aggregate.sort({ field: 'asc', test: -1 });
aggregate.sort('field -test');

Aggregate.prototype.read()¶

参数

[tags] «Array» optional tags for this query

Sets the readPreference option for the aggregation query.

示例

Model.aggregate(..).read('primaryPreferred').exec(callback)

Aggregate.prototype.explain()¶

参数

返回

Execute the aggregation with explain

示例

Model.aggregate(..).explain(callback)

Aggregate.prototype.allowDiskUse()¶

参数

[tags] «Array» optional tags for this query

Sets the allowDiskUse option for the aggregation query (ignored for < 2.6.0)

示例

Model.aggregate(..).allowDiskUse(true).exec(callback)

Aggregate.prototype.option()¶

参数

value «Object» keys to merge into current options

返回

Lets you set arbitrary options, for middleware or plugins.

示例

var agg = Model.aggregate(..).option({ allowDiskUse: true });
agg.options;

Aggregate.prototype.cursor()¶

参数

[options.useMongooseAggCursor] «Boolean» use experimental mongoose-specific aggregation cursor (for eachAsync() and other query cursor semantics)

Sets the cursor option option for the aggregation query (ignored for < 2.6.0). Note the different syntax below: .exec() returns a cursor object, and no callback is necessary.

示例

var cursor = Model.aggregate(..).cursor({ batchSize: 1000 }).exec();
cursor.each(function(error, doc) {

});

Aggregate.prototype.addCursorFlag()¶

参数

Adds a [cursor flag

示例

Model.aggregate(..).addCursorFlag('noCursorTimeout', true).exec();

Aggregate.prototype.collation()¶

参数

Adds a collation

示例

Model.aggregate(..).collation({ locale: 'en_US', strength: 1 }).exec();

Aggregate.prototype.facet()¶

参数

返回

Combines multiple aggregation pipelines.

示例

Model.aggregate(...)
 .facet({
   books: [{ groupBy: '$author' }],
   price: [{ $bucketAuto: { groupBy: '$price', buckets: 2 } }]
 })
 .exec();

Aggregate.prototype.pipeline()¶

返回

Returns the current pipeline

示例

MyModel.aggregate().match({ test: 1 }).pipeline();

Aggregate.prototype.exec()¶

参数

返回

Executes the aggregate pipeline on the currently bound Model.

示例

aggregate.exec(callback);

var promise = aggregate.exec();
promise.then(..);

Aggregate.prototype.then()¶

参数

[reject] «Function» errorCallback

返回

Provides promise for aggregate.

示例

Model.aggregate(..).then(successCallback, errorCallback);