code: protected function getDepDropParents($post = 'depdrop_parents')
      {
          $parents = Yii::$app->request->post($post);
          $filteredParents = [];
          foreach ($parents as $key => $parent) {
              if (is_numeric($parent)) {
                  $filteredParents[$key] = $parent;
              } else {
                  return [];
              }
          }
          return $filteredParents;
      }
docs: Get a filtered array of valid values set by depdrop.
  
  @return array