Firebase Streambuilder is not changing login state after navigating - firebase

Question

Here, i am trying to implement Firebase login and signup system. i am trying to change screen base on user login or not.
Basically, i want to show feed screen when user is login and when user is not login i want to show login scree. if i do login in login screen it is working fine, so i did not added that code here. but issue come when i navigate from login screen to sign up scree and even if i successfully sign up it is not showing me feed screen. When i hot reload it show me feed screen.
Moreover, i also make sure that it is reaching where i am changing screen by print in console.
Note: i know i can using function to change between login screen and signup screen, so i don't need Navigator, which will again work for me. but i want to know why after navigating using navigator it is not working.
class DeleteWidget extends StatefulWidget {
#override
_DeleteWidgetState createState() => _DeleteWidgetState();
}
class _DeleteWidgetState extends State<DeleteWidget> {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: StreamBuilder<FirebaseUser>(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (BuildContext context, snapshot) {
print(snapshot.hasData);
print(snapshot.connectionState);
if (ConnectionState.active == snapshot.connectionState) {
print("object 1");
if (snapshot.hasData) {
print("object 2");
return Feed();
} else {
print("object 3");
return LoginScreen();
}
} else {
return LoginScreen();
}
}),
);
}
}
class LoginScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
child: RaisedButton(
child: Text("login"),
onPressed: () async {
Navigator.push(
context, MaterialPageRoute(builder: (context) => SignUp()));
},
),
),
),
);
}
}
class SignUp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
child: RaisedButton(
child: Text("Sign up"),
onPressed: () async {
await FirebaseAuth.instance.signInAnonymously();
},
),
),
),
);
}
}
class Feed extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
child: RaisedButton(
child: Text("feed"),
onPressed: () async {
await FirebaseAuth.instance.signOut();
},
),
),
),
);
}
}

Answer 1

You can use the Provider Package to Listen if user is logged in and use a Wrapper to direct the user to the correct screen. If the user logs out at any stage, they will be automatically redirected to the Login Screen.
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
User _userFromFirebaseUser(FirebaseUser user) {
return user != null ? User(uid: user.uid) : null;
}
#override
Widget build(BuildContext context) {
return StreamProvider<User>.value(
value: FirebaseAuth.instance.onAuthStateChanged.map(_userFromFirebaseUser),
child: MaterialApp(
home: Wrapper(),
),
);
}
}
Wrapper
class Wrapper extends StatelessWidget {
#override
Widget build(BuildContext context) {
final user = Provider.of<User>(context);
if(user == null) {
return LoginScreen();
} else {
return Feed();
}
}
}