protected function getData()
    {
        $data = [];
        foreach ($this->_schema as $name => $desc) {
            $data[$name] = $this->$name;
            if (isset($desc['updateDate']) && $desc['updateDate']) {
                $data[$name] = new MongoDate();
            }
        }
        if ($data['_id'] === null) {
            // @codeCoverageIgnoreStart
            unset($data['_id']);
            // @codeCoverageIgnoreEnd
        }
        return $data;
    }