public function get_baselayers(DataContainer $dc)
    {
        $id = 0;
        if ($dc->activeRecord->c4g_map_id != 0) {
            $id = $dc->activeRecord->c4g_map_id;
        } else {
            // take firstMapId, because it will be chosen as DEFAULT value for c4g_map_id
            $id = $this->firstMapId;
        }

        $profile = $this->Database->prepare(
                "SELECT b.baselayers ".
                "FROM tl_c4g_maps a, tl_c4g_map_profiles b ".
                "WHERE a.id = ? and a.profile = b.id")
                ->execute($id);

        $ids = deserialize($profile->baselayers,true);
        if (count($ids)>0) {
            $baseLayers = $this->Database->prepare("SELECT id,name FROM tl_c4g_map_baselayers WHERE id IN (".implode(',',$ids).") ORDER BY name")->execute();
        } else {
            $baseLayers = $this->Database->prepare("SELECT id,name FROM tl_c4g_map_baselayers ORDER BY name")->execute();
        }


        if ($baseLayers->numRows > 0) {
            while ( $baseLayers->next () ) {
                $return [$baseLayers->id] = $baseLayers->name;
            }
        }
        return $return;
    }