/**
  * Finds the Cover model based on its primary key value.
  * If the model is not found, a 404 HTTP exception will be thrown.
  * @param integer $id
  * @return Cover the loaded model
  * @throws NotFoundHttpException if the model cannot be found
  */
 protected function findModel($id)
 {
     if (($model = Cover::findOne($id)) !== null) {
         if ($model->file->user_id != Yii::$app->user->id) {
             throw new \yii\web\ForbiddenHttpException();
         }
         return $model;
     } else {
         throw new \yii\web\NotFoundHttpException('The requested page does not exist.');
     }
 }
 public function actionCover()
 {
     $model = Cover::findOne(Yii::$app->request->post('pk', ''));
     $ownerId = $model->file->user_id;
     return self::update($model, $ownerId);
 }