gistfile1.php

<?php

class MyExcel {

    public static function setContent(sfEvent $event, $response) {
        if (in_array(self::$format, self::$acceptedFormats)) {
            //add content file
            $doc = new ZipArchive();
            $doc->open(sfConfig::get('sf_data_dir') . '/documents/report/my_report.ods');
            $doc->addFromString('content.xml', $response);
            $doc->close();
        }

        if(self::$format == 'ods'){
            $response = file_get_contents(sfConfig::get('sf_data_dir') . '/documents/report/my_report.ods');
        }
        /* ... deal with other formats ... */
        return $response;
}