public function createQuery($context = 'list')
    {
        $query = parent::createQuery($context);
        $query->leftJoin($query->getRootAlias().'.article', 'article')->addSelect('article')
              ->leftJoin($query->getRootAlias().'.parent', 'parent')->addSelect('parent')
              ->leftJoin($query->getRootAlias().'.children', 'children')->addSelect('children')
              ->orderBy($query->getRootAlias().'.root, '.$query->getRootAlias().'.lft', 'ASC');

        return $query;
    }