How to check user is logged in or not with firebase for web App in flutter?

Question

I have authenticated into firebase for the futter Web App as well as mobile platform App. but whenever rebuild or re-run the Web App it takes me to the login screen but I have implemented code for the user logged in or not but is not working. it should navigate to home screen.

piece of Code:

class LandingScreen extends StatefulWidget {
 @override
 _LandingScreenState createState() => _LandingScreenState();
}

class _LandingScreenState extends State<LandingScreen> {
 bool isLoggedIn = false;
 FirebaseUser _user;
@override
 void initState() {
   super.initState();
   FirebaseAuth.instance.currentUser().then((user) {
    if(user!=null){
      print("user:${user.uid}");
      setState(() {
        _user = user;
        isLoggedIn=true;
      });
     //  Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(
     //    builder: (context)=>HomeScreen(user: user)), (route) => false);
    }else{
      setState(() {
        isLoggedIn = false;
      });
       // Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(
       //  builder: (context)=>LoginScreen()), (route) => false);
    }
   });
 }
 @override
  Widget build(BuildContext context){
   return isLoggedIn?HomeScreen(user: _user):LoginScreen();
   
 }
}

Answer 1

Try removing setState. SetState tells the widget to rebuild but InitState runs before the widget is built in the first place so it's not having an effect here. It might not fix the issue though.

Answer 2

Try the following:

  @override
  void initState() {
    super.initState();
    FirebaseAuth.instance.currentUser().then((res) {
      print(res);
      if (res != null) {
        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => Home(user: res)),
        );
      }
      else
      {
        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => LoginScreen()),
        );
      }
    });
  }

currentUser() is asynchronous therefore inside the then() navigate to the different pages according to the result