doctrine / mongodb-odm

     * @param string|array|null $expression Optional. A replacement expression that

     * resolves to a document.

     */

    public function replaceRoot($expression = null) : Stage\ReplaceRoot

    {

        $stage = new Stage\ReplaceRoot($this, $this->dm, $this->class, $expression);

        $this->addStage($stage);

        return $stage;

    }

    /**

     * Randomly selects the specified number of documents from its input.

     *

     * @see http://docs.mongodb.org/manual/reference/operator/aggregation/sortByCount/

     */

    public function sortByCount(string $expression) : Stage\SortByCount

    {

        $stage = new Stage\SortByCount($this, $expression, $this->dm, $this->class);

        $this->addStage($stage);

        return $stage;

    }

    /**

     * Deconstructs an array field from the input documents to output a document