protected function _defaultData($content)
    {
        $content = @unserialize($content);
        if (empty($content) || !is_a($content, \stdClass::class)) {
            $content = new \stdClass;
        }
        $content->file = empty($content->file) ? '' : $content->file;
        $content->title = empty($content->title) ? '' : $content->title;
        return $content;
    }