My code is like this

class MyApp extends StatelessWidget {
  MyApp({Key? key}) : super(key: key);

  Future<String> validation() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    bool isWTdone = prefs.getBool('WT') ?? false;
    bool isLoggedIn = prefs.getString('email') == null ? false : true;

    if(isWTdone){
      if(isLoggedIn)
      {
        return '/home';
      }
        return '/login';
    }
      return '/';
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      navigatorObservers: [
        locator<AnalyticsService>().getanalyticsObserver(),
      ],
      //iswalkthrough and islogin
      initialRoute: validation(),
      routes: appRoutes,
    );
  }
}

in the initalRoute line it gives me this error:

The argument type 'Future' can't be assigned to the parameter type 'String?'.

Can anyone know how can i fix this? my goal is to determine the initalRoute from the output of the SharedPreference

CodePudding user response：

Try to wrap MaterialApp to FutureBuilder or perform your async code in main.dart before calling runApp. You can pass needed value to the MyApp through the constructor.

CodePudding user response：

Yup, that's because the method validation is a future and to use it you have to write await validation() and that cannot be done directly inside the widget tree, a solution I suggest;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  final prefs = await SharedPreferences.getInstance();
  bool isWTdone = prefs.getBool('WT') ?? false;
  bool isLoggedIn = prefs.getString('email') == null ? false : true;
  late final initialRoute;

  if (isWTdone) {
    if (isLoggedIn)
      initialRoute = '/home';
    else
      initialRoute = '/login';
  } else
    initialRoute = '/';

  return runApp(MyApp(initialRoute: initialRoute));
}

class MyApp extends StatelessWidget {
  final String initialRoute;

  const MyApp({Key? key, required this.initialRoute}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      navigatorObservers: [
        locator<AnalyticsService>().getanalyticsObserver(),
      ],
      //iswalkthrough and islogin
      initialRoute: validation(),
      routes: appRoutes,
    );
  }
}

What I've done here, is I initialized the initialRoute before the runApp and passed to the MyApp Stateless Widget

CodePudding user response：

Set the initialRoute to a route of a Splash Screen. Inside that screen you should call your validation() function inside initState and depending on your output you navigate to whatever screen you want to. I don't think using an async method inside your MaterialApp widget is encouraged so try to implement this inside a Splash Screen and you'll be fine.