public function onSubmitCallback(DataContainer $dc)
    {
        // Return if the user is allowed to assign categories or the record is not new
        if ($this->permissionChecker->canUserAssignCategories() || $dc->activeRecord->tstamp > 0) {
            return;
        }

        $dc->field = 'categories';

        $relations = new Relations();
        $relations->updateRelatedRecords($this->permissionChecker->getUserDefaultCategories(), $dc);

        // Reset back the field property
        $dc->field = null;
    }