public static function toCsv($file) { $splitted = explode(".", $file->filename); $extension = end($splitted); switch ($extension) { case 'csv': return $file->getBytes(); case 'xls': return CommonTools::xlsToCsv($file, 'Excel5'); case 'xlsx': return CommonTools::xlsToCsv($file, 'Excel2007'); default: Yii::app()->user->setFlash('error', "bad extension :{$extension} , {$file->filename}"); } return null; }