public function run()
 {
     $comments = Comment::childClass(true)->search()->orderBy(['created_at' => SORT_DESC])->where(['parent_class' => $this->parent->className(), 'parent_id' => $this->parent->primaryKey, 'status' => Comment::STATUS_ACTIVE])->with('user')->all();
     if (!$comments) {
         return;
     }
     return $this->render($this->viewFile, compact('comments'));
 }
 public function down()
 {
     $this->dropTable(Comment::tableName());
 }