public function saveGridOrder() {
        if (!isset(Yii::$app->session[$this->sessionVarName])) {
            Yii::$app->session[$this->sessionVarName] = '';
        }

        if (Yii::$app->request->get($this->getVarName) !== null) {
            Yii::$app->session[$this->sessionVarName] = Yii::$app->request->get($this->getVarName);
        }
    }