public function change(Event $event, ProfferPath $path) { // Detect and select the right file extension $type = $event->subject()[$path->getField()]['type']; switch ($type) { default: case "image/jpeg": $ext = '.jpg'; break; case "image/png": $ext = '.png'; break; case "image/gif": $ext = '.gif'; break; } $newFilename = md5(uniqid(true)) . $ext; $path->setFilename($newFilename); $event->subject()[$path->getField()]['name'] = $newFilename; return $path; }