How can I access and adjust provider inside main() or runApp() to apply the value from firebase auth?

Question

  FirebaseAuth.instance.authStateChanges().listen((User? user) {
    if (user == null) {
      print('User is currently signed out!');
    } else {
      print('User is signed in!');
    }
  });

I have this function inside the main() {}. I want to change riverpod state when it detects changes to Firebase Auth. But, right now I am stuck because I can't access my riverpod state without using WidgetRef ref that uses widget.

If I put that into my main widget, then there is a bit of a delay. Or, is this not recommended to do - putting firebase.auth function inside the main()?

Answer 1

This function shouldn't be in your main func, what you can do is to modify your main.dart to look like this:

void updateState(WidgetRef ref) {
FirebaseAuth.instance.authStateChanges().listen((User? user) {
    if (user == null) {
      print('User is currently signed out!');
      ///update state with ref....

    } else {
      print('User is signed in!');

      ///update state with ref....

    }
  });
}
    void main() {
      runApp(const ProviderScope(child: MyApp()));
    }
    
    class MyApp extends ConsumerWidget {
      const MyApp({super.key});
    
      // This widget is the root of your application.
      @override
      Widget build(BuildContext context, WidgetRef ref) {
    
        WidgetsBinding.instance.addPostFrameCallback((_) {
         updateState(ref);
        });
        return MaterialApp(
          title: 'Flutter Demo',
          theme: MyTheme.appTheme,
          debugShowCheckedModeBanner: false,
          home: const HomeScreen(),
        );
      }
    }

Another approach could be to use an initstate in a ConsumerStatefulWidget, would look like:

  void updateState(WidgetRef ref) {
FirebaseAuth.instance.authStateChanges().listen((User? user) {
    if (user == null) {
      print('User is currently signed out!');
      ///update state with ref....

    } else {
      print('User is signed in!');

      ///update state with ref....

    }
  });
}
    void main() {
      runApp(const ProviderScope(child: MyApp()));
    }
    
    class MyApp extends ConsumerStatefulWidget {
      const MyApp({super.key});
    
      @override
      ConsumerState<MyApp> createState() => _MyAppState();
    }
    
    class _MyAppState extends ConsumerState<MyApp> {
      // This widget is the root of your application.
    
      @override
      void initState() {
        // TODO: implement initState
        updateState(ref);
        super.initState();
      }
    
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter Demo',
          theme: MyTheme.appTheme,
          debugShowCheckedModeBanner: false,
          home: const HomeScreen(),
        );

  }
}