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MongoDB\Collection::aggregate()

Definition

MongoDB\Collection::aggregate

Executes an aggregation framework pipeline operation on the collection.

function aggregate(array $pipeline, array $options = []): Traversable

This method has the following parameters:

Parameter Type Description
$pipeline array Specifies an aggregation pipeline operation.
$options array Optional. An array specifying the desired options.

The $options parameter supports the following options:

Option Type Description
allowDiskUse boolean Optional. Enables writing to temporary files. When set to true, aggregation stages can write data to the _tmp sub-directory in the dbPath directory. The default is false.
batchSize integer Optional. Specifies the initial batch size for the cursor. A batchSize of 0 means an empty first batch and is useful for quickly returning a cursor or failure message without doing significant server-side work.
bypassDocumentValidation boolean

Optional. If true, allows the write operation to circumvent document level validation. Defaults to false.

This option is available in MongoDB 3.2+ and is ignored for older server versions, which do not support document level validation.

This only applies when using the $out stage.

Document validation requires MongoDB 3.2 or later: if you are using an earlier version of MongoDB, this option will be ignored.

comment string

Optional. Users can specify an arbitrary string to help trace the operation through the database profiler, currentOp, and logs.

New in version 1.3.

explain boolean

Optional. Specifies whether or not to return the information on the processing of the pipeline.

New in version 1.4.

hint string|array|object

Optional. The index to use. Specify either the index name as a string or the index key pattern as a document. If specified, then the query system will only consider plans using the hinted index.

New in version 1.3.

maxTimeMS integer Optional. The cumulative time limit in milliseconds for processing operations on the cursor. MongoDB aborts the operation at the earliest following interrupt point.
readConcern MongoDB\Driver\ReadConcern

Optional. Read concern to use for the operation. Defaults to the collection’s read concern.

This is not supported for server versions prior to 3.2 and will result in an exception at execution time if used.

readPreference MongoDB\Driver\ReadPreference

Optional. Read preference to use for the operation. Defaults to the collection’s read preference.

This option will be ignored when using the $out stage.

session MongoDB\Driver\Session

Optional. Client session to associate with the operation.

Sessions are not supported for server versions prior to 3.6.

New in version 1.3.

typeMap array Optional. The type map to apply to cursors, which determines how BSON documents are converted to PHP values. Defaults to the collection’s type map.
useCursor boolean Optional. Indicates whether the command will request that the server provide results using a cursor. The default is true.
writeConcern MongoDB\Driver\WriteConcern

Optional. Write concern to use for the operation. Defaults to the collection’s write concern.

This only applies when the $out stage is specified.

This is not supported for server versions prior to 3.4 and will result in an exception at execution time if used.

Return Values

A MongoDB\Driver\Cursor or ArrayIterator object. In both cases, the return value will be Traversable.

Errors/Exceptions

MongoDB\Exception\UnexpectedValueException if the command response from the server was malformed.

MongoDB\Exception\UnsupportedException if options are used and not supported by the selected server (e.g. collation, readConcern, writeConcern).

MongoDB\Exception\InvalidArgumentException for errors related to the parsing of parameters or options.

MongoDB\Driver\Exception\RuntimeException for other errors at the driver level (e.g. connection errors).

Behavior

MongoDB\Collection::aggregate()’s return value depends on the MongoDB server version and whether the useCursor option is specified. If useCursor is true, a MongoDB\Driver\Cursor object is returned. If useCursor is false, an ArrayIterator is returned that wraps the result array from the command response document. In both cases, the return value will be Traversable.

See Also