code: public function actionList()
      {
          Yii::$app->response->format = Response::FORMAT_JSON;
          $parents = $this->getDepDropParents();
          if (count($parents) < 2) {
              $output = [];
          } else {
              $searchParents = ['country_id' => $parents[0]];
              if (isset($parents[1])) {
                  $searchParents['state_id'] = $parents[1];
              } elseif (isset($parents[2])) {
                  $searchParents['region_id'] = $parents[2];
              }
              $searchModel = new SearchCity($searchParents);
              $dataProvider = $searchModel->search(Yii::$app->request->queryParams);
              $dataProvider->setPagination(false);
              $dataProvider->getSort()->defaultOrder = ['name' => SORT_ASC];
              $output = ArrayHelper::toArray($dataProvider->getModels(), ['id', 'name']);
          }
          return [
              'output' => $output
          ];
      }
docs: Gets a json list of the countries in the database.
  
  @return array