/**
  * Updates an existing Rate 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()) {
         return $this->redirect(['view', 'id' => $model->id]);
     } else {
         $currency_list = Currency::getCurrencyList();
         return $this->render('update', ['model' => $model, 'currency' => $currency_list]);
     }
 }