/**
     * @return $this
     */
    public function withFiles() {
        $this->onPostFetch[] = function(\Kdyby\Persistence\Query $self, \Kdyby\Persistence\Queryable $repository, \Iterator $iterator) {
            $ids = array_map(function($row) {
                return $row->id;
            }, iterator_to_array($iterator));

            $repository->createQueryBuilder('e')->select('e.id')
                ->leftJoin('e.files', 'f')
                ->andWhere('e.id IN (:ids)', $ids)
                ->addGroupBy('e.id')
                ->getQuery()
                ->getResult();
        };

        return $this;
    }