public function get_file_content() {
        $dir = make_request_directory();
        $filename = $dir . '/result.ods';

        $files = [
                'mimetype'              => [$this->get_ods_mimetype()],
                'content.xml'           => [$this->get_ods_content($this->worksheets)],
                'meta.xml'              => [$this->get_ods_meta()],
                'styles.xml'            => [$this->get_ods_styles()],
                'settings.xml'          => [$this->get_ods_settings()],
                'META-INF/manifest.xml' => [$this->get_ods_manifest()],
            ];

        $packer = get_file_packer('application/zip');
        $packer->archive_to_pathname($files, $filename);

        $contents = file_get_contents($filename);

        remove_dir($dir);
        return $contents;
    }