import 'dart:math'; const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890_'; Random _rnd = Random(); String getRandomString(int length) => String.fromCharCodes( Iterable.generate( length, (_) => _chars.codeUnitAt( _rnd.nextInt(_chars.length), ), ), );