public function performAjaxValidation($post=null)
    {
        $request = Yii::$app->getRequest();

        /**
         * @var $this \yii\base\Model
         */
        if ($request->isAjax && $this->load(isset($post) ? $post : $request->post())) {
            $response = Yii::$app->getResponse();
            $response->format = $response::FORMAT_JSON;
            if (is_null($this->_performAjaxValidationResult)){
                $this->_performAjaxValidationResult = ActiveForm::validate($this);
            }
            return $this->_performAjaxValidationResult;
        }
        return null;
    }