public function export_file_for_engine($file) {
        $data = $this->export_for_engine();

        // Content is index in the main document.
        unset($data['content']);
        unset($data['description1']);
        unset($data['description2']);

        // Going to append the fileid to give it a unique id.
        $data['id'] = $data['id'].'-solrfile'.$file->get_id();
        $data['type'] = \core_search\manager::TYPE_FILE;
        $data['solr_fileid'] = $file->get_id();
        $data['solr_filecontenthash'] = $file->get_contenthash();
        $data['solr_fileindexstatus'] = self::INDEXED_FILE_TRUE;
        $data['title'] = $file->get_filename();
        $data['modified'] = self::format_time_for_engine($file->get_timemodified());

        return $data;
    }