/** * @return mixed|string * @throws InvalidConfigException * @throws \yii\web\NotFoundHttpException */ public function run() { if ($this->callback) { if (!is_callable($this->callback)) { throw new InvalidConfigException('"' . get_class($this) . '::callback" ' . \Yii::t('app', 'should be a valid callback.')); } return call_user_func($this->callback, $this); } return parent::run(); }