/**
  * Updates an existing ClassRooms model.
  * If update is successful, the browser will be redirected to the 'view' page.
  * @param integer $id
  * @return mixed
  */
 public function actionUpdate($id)
 {
     $model = $this->findModel($id);
     if ($model->load(Yii::$app->request->post()) && $model->save()) {
         ClassType::deleteAll('classroom_id = ' . $model->classrooms_id);
         $spec_classes_array = $model->options;
         foreach ($spec_classes_array as $key) {
             $ctype = new ClassType();
             $ctype->classroom_id = $model->classrooms_id;
             $ctype->spec_class_id = $key;
             $ctype->insert();
         }
         return $this->redirect(['view', 'id' => $model->classrooms_id]);
     } else {
         $opt = ClassType::findAll(['classroom_id' => $_GET['id']]);
         foreach ($opt as $key) {
             $optArr[] = $key['spec_class_id'];
         }
         $model->options = $optArr;
         return $this->render('update', ['model' => $model]);
     }
 }