public function actionSetIdentity()
    {
        $user_id = Yii::$app->request->post('user_id');

        $userSwitch = new UserSwitch();
        $newIdentity = Yii::$app->user->identity->findIdentity($user_id);
        $userSwitch->setUserByIdentity($newIdentity);
        return Yii::$app->user;
    }