/**
  * Extend so the foreign key is correctly flagged.
  *
  * @param string $model
  * @param null   $alias
  *
  * @return array
  */
 protected function getModelFields($model, $alias = null)
 {
     $fields = parent::getModelFields($model, $alias);
     $fields['categoryId']['type'] = 'foreignKey';
     return $fields;
 }