public function __construct($id = null)
 {
     if (!isset(self::$tempPath)) {
         self::$tempPath = LudoDBRegistry::get(self::FILE_UPLOAD_KEY);
         if (!isset(self::$tempPath)) {
             throw new Exception("Temp path for file uploads not set. Use LudoDBRegistry::set(self::FILE_UPLOAD_KEY, 'your/path'); to set path", 500);
         }
     }
     parent::__construct($id);
 }