Yii Restful. Exception "setting Unknown Property" When Try To Override Action In Activecontroller

I am learning implementing restful web service using Yii2. In following controller, I am trying to override the ‘index’ action. But I encountered following error. Anyone can give me some clue? Thanks.

Unknown Property – yii\base\UnknownPropertyException

Setting unknown property: api\modules\v1\controllers\CountryController::checkAccess


namespace api\modules\v1\controllers;

use yii\data\ActiveDataProvider;

use yii\rest\ActiveController;

class CountryController extends ActiveController


    public $modelClass = 'api\modules\v1\models\Country';

    public $serializer = [

        'class' => 'yii\rest\Serializer',

        'collectionEnvelope' => 'items',


    //-- disable, override or add actions

    //-- when overriding default action, make sure current controller has checkAccess() method implemented

    public function actions()


        $actions = parent::actions();

        //-- override default actions with actions in this controller

        $actions['index'] = [

            'class' => $this->className(),

            'modelClass' => $this->modelClass,

            'checkAccess' => [$this, 'checkAccess'],


        return $actions;


    public function actionIndex()


        return new ActiveDataProvider(['query' => Country::find()]);


    public function checkAccess($action, $model = null, $params = [])


        //--check if the user can access $action & $model

        //--throw ForbiddenHttpException if access should be denied

        return true;