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MongoDB\\Database::listCollectionNames()
========================================

.. versionadded:: 1.7

.. default-domain:: mongodb

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   :class: singlecol

Definition
----------

.. phpmethod:: MongoDB\\Database::listCollectionNames()

   Returns names for all collections in this database.

   .. code-block:: php

      function listCollectionNames(array $options = []): Iterator

   This method has the following parameters:

   .. include:: /includes/apiargs/MongoDBDatabase-method-listCollections-param.rst

   The ``$options`` parameter supports the following options:

   .. include:: /includes/apiargs/MongoDBDatabase-method-listCollections-option.rst

Return Values
-------------

An :php:`Iterator <class.iterator.php>`, which provides the name of each
collection in the database.

Example
-------

The following example lists all of the collections in the ``test`` database:

.. code-block:: php

   <?php

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

   foreach ($database->listCollectionNames() as $collectionName) {
       var_dump($collectionName);
   }

The output would then resemble::

   string(11) "restaurants"
   string(5) "users"
   string(6) "restos"

The following example lists all collections whose name starts with ``"rest"``
in the ``test`` database:

.. code-block:: php

   <?php

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

   $collections = $database->listCollectionNames([
       'filter' => [
           'name' => new MongoDB\BSON\Regex('^rest.*'),
       ],
   ]);

   foreach ($collections as $collectionName) {
       var_dump($collectionName);
   }

The output would then resemble::

   string(11) "restaurants"
   string(6) "restos"

.. note::

   When enumerating collection names, a filter expression can only filter based
   on a collection's name and type. No other fields are available.

See Also
--------

- :phpmethod:`MongoDB\\Database::listCollections()`
- :manual:`listCollections </reference/command/listCollections` command
  reference in the MongoDB manual
- `Enumerating Collections
  <https://github.com/mongodb/specifications/blob/master/source/enumerate-collections.rst>`_
  specification