public function currencyValidator($attr)
 {
     if (!$this->hasErrors($attr)) {
         $this->_currency = Currency::find()->active()->andWhere(['id' => $this->{$attr}])->limit(1)->one();
         if (!$this->_currency) {
             $this->addError($attr, 'There is no such currency');
             return false;
         }
         $user = $this->_currency->user;
         if (!$user) {
             $this->addError($attr, 'There is no such currency');
             return false;
         }
         if (!$this->_user->isInSameGroup($user)) {
             $this->addError($attr, 'This currency belongs to another User');
             return false;
         }
     }
 }
 public function actionIndex()
 {
     $currency = Currency::find()->active()->forUsersInSameGroup($this->_user)->expand(Yii::$app->request->getQueryParams())->asArray()->all();
     return ['status' => true, 'data' => $currency];
 }