MongoDB\Database::aggregate()

Definition

MongoDB\Database::aggregate()

Runs a specified admin/diagnostic pipeline which does not require an underlying collection. For aggregations on collection data, see MongoDB\Collection::aggregate().

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

Parameters

$pipeline : array|Pipeline

Specifies an aggregation pipeline operation. You can include aggregation stages in a MongoDB\Builder\Pipeline instance or in an array.

$options : array

An array specifying the desired options.

Name	Type	Description
allowDiskUse	boolean	Enables writing to temporary files. When set to true, aggregation stages can write data to the _tmp sub-directory in the dbPath directory.
batchSize	integer	The maximum number of documents within each batch returned in a query result. By default, the aggregate command has an initial batch size of 101 documents and a maximum size of 16 mebibytes (MiB) for each subsequent batch. This option can enforce a smaller limit than 16 MiB, but not a larger one. If you set batchSize to a limit that results in batches larger than 16 MiB, this option has no effect. A batchSize of 0 means that the cursor will be established, but no documents will be returned in the first batch. This may be useful for quickly returning a cursor or failure from aggregate without doing significant server-side work.
bypassDocumentValidation	boolean	If true, allows the write operation to circumvent document level validation. Defaults to false. This only applies when using the $out and $out stages.
codec	MongoDB\Codec\DocumentCodec	The codec to use for encoding or decoding documents. This option is mutually exclusive with the typeMap option. New in version 1.17.
collation	array|object	Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks. When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.
comment	mixed	Enables users to specify an arbitrary comment to help trace the operation through the database profiler, currentOp output, and logs. The comment can be any valid BSON type for server versions 4.4 and above. Earlier server versions only support string values.
explain	boolean	Specifies whether or not to return the information on the processing of the pipeline.
hint	string|array|object	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.
let	array|object	Map of parameter names and values. Values must be constant or closed expressions that do not reference document fields. Parameters can then be accessed as variables in an aggregate expression context (e.g. $$var). This is not supported for server versions prior to 5.0 and will result in an exception at execution time if used. New in version 1.9.
maxTimeMS	integer	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	Read concern to use for the operation. Defaults to the database's read concern.
readPreference	MongoDB\Driver\ReadPreference	Read preference to use for the operation. Defaults to the database's read preference.
session	MongoDB\Driver\Session	Client session to associate with the operation.
typeMap	array	The type map to apply to cursors, which determines how BSON documents are converted to PHP values. Defaults to the database's type map.
writeConcern	MongoDB\Driver\WriteConcern	Write concern to use for the operation. Defaults to the database's write concern.

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 extension level (e.g. connection errors).

Examples

The following aggregation example lists all running commands using the $currentOp aggregation pipeline stage, then filters this list to only show running command operations.

<?php
$database = (new MongoDB\Client)->admin;
$cursor = $database->aggregate(
    [
        ['$currentOp' => []],
        ['$match' => ['op' => 'command']],
    ]
);

See Also

• Transform Your Data with Aggregation

• MongoDB\Collection::aggregate()

• aggregate command reference in the MongoDB manual

• Aggregation Pipeline documentation in the MongoDB Manual