public function reorder($photo_ids)
    {
        if (count($photo_ids) == 1) {
            if ($edge = $this->getService('repos:photos.edge')
                              ->fetch(array(
                                        'set' => $this,
                                        'photo.id' => $photo_ids[0],
                                      ))
            ) {
                $edge->ordering = $this->photos->getTotal();
            }

            return;
        }

        foreach ($photo_ids as $index => $photo_id) {
            if ($edge = $this->getService('repos:photos.edge')
                             ->fetch(array(
                                      'set' => $this,
                                      'photo.id' => $photo_id, ))
            ) {
                $edge->ordering = $index + 1;
            }
        }
    }