Finds a single document from the GridFS bucket’s files collection matching the query.

function findOne(array|object $filter = [], array $options = []): array|object|null

This method has the following parameters:

Parameter Type Description
$filter array|object Optional. The filter criteria that specifies the documents to query.
$options array Optional. An array specifying the desired options.

The $options parameter supports the following options:

Option Type Description
projection array|object Optional. The projection specification to determine which fields to include in the returned documents. See Project Fields to Return from Query and Projection Operators in the MongoDB manual.
sort array|object Optional. The sort specification for the ordering of the results.
skip integer Optional. Number of documents to skip. Defaults to 0.
allowDiskUse boolean Optional. Enables writing to temporary files. When set to true, queries can write data to the _tmp sub-directory in the dbPath directory.
collation array|object

Optional. 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.

If the collation is unspecified but the collection has a default collation, the operation uses the collation specified for the collection. If no collation is specified for the collection or for the operation, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

comment mixed

Optional. 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.

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.

It is not possible to specify a read concern for individual operations as part of a transaction. Instead, set the readConcern option when starting the transaction with startTransaction.

readPreference MongoDB\Driver\ReadPreference Optional. Read preference to use for the operation. Defaults to the bucket’s read preference.
typeMap array

Optional. The type map to apply to cursors, which determines how BSON documents are converted to PHP values. Defaults to the bucket’s type map.

This will be used for the returned result document.

modifiers array|object Optional. Meta operators that modify the output or behavior of a query. Use of these operators is deprecated in favor of named options.

Return Values

An array or object for the first document that matched the query, or null if no document matched the query. The return type will depend on the typeMap option.


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).


When evaluating query criteria, MongoDB compares types and values according to its own comparison rules for BSON types, which differs from PHP’s comparison and type juggling rules. When matching a special BSON type the query criteria should use the respective BSON class in the driver (e.g. use MongoDB\BSON\ObjectId to match an ObjectId).



$bucket = (new MongoDB\Client)->test->selectGridFSBucket();

$stream = fopen('php://temp', 'w+b');
fwrite($stream, "foobar");

$bucket->uploadFromStream('b', $stream);

$fileDocument = $bucket->findOne(
    ['length' => ['$lte' => 6]],
        'projection' => [
            'filename' => 1,
            'length' => 1,
            '_id' => 0,
        'sort' => ['length' => -1],


The output would then resemble:

object(MongoDB\Model\BSONDocument)#3004 (1) {
  array(2) {
    string(1) "b"