create_time = time(); } public function beforeUpdate() { $this->update_time = time(); } public static function itemTypes() { return [ self::ITEM_USER => '用户', self::ITEM_GROUP => '群组', self::ITEM_COURSE => '课程', self::ITEM_CHAPTER => '章节', self::ITEM_CONSULT => '咨询', self::ITEM_REVIEW => '评价', self::ITEM_ARTICLE => '文章', self::ITEM_QUESTION => '提问', self::ITEM_ANSWER => '回答', self::ITEM_COMMENT => '评论', ]; } }