public function getId()
    {
        $class = get_called_class();

        if (isset($this->cleanData['_id'])) {
            if($class::$customIdType === true) return $this->cleanData['_id'];

            return new \MongoId($this->cleanData['_id']);
        } elseif (isset($this->_tempId)) {
            return $this->_tempId;
        }

        return null;
    }