public function get_tempfiles($skipfile='portfolio-export.zip') {
        $fs = get_file_storage();
        $files = $fs->get_area_files(SYSCONTEXTID, 'portfolio', 'exporter', $this->id, 'sortorder, itemid, filepath, filename', false);
        if (empty($files)) {
            return array();
        }
        $returnfiles = array();
        foreach ($files as $f) {
            if ($f->get_filename() == $skipfile) {
                continue;
            }
            $returnfiles[$f->get_filepath() . $f->get_filename()] = $f;
        }
        return $returnfiles;
    }