Implement verification user exist - flutter

Question

I would like to check if the user has already filled in the registration form:
Here is my code for the connectionState:
class LandingPage extends StatelessWidget {
// final Geolocator _geolocator = Geolocator()..forceAndroidLocationManager;
#override
Widget build(BuildContext context) {
final auth = Provider.of<AuthBase>(context, listen: false);
return StreamBuilder<User>(
stream: auth.onAuthStateChanged,
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.active) {
User user = snapshot.data;
if (user == null) {
return SignInPage();
} else {
// _geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.best)
MatchEngine.instance.initialise(user.uid);
return Chat();
}
} else {
return Scaffold(
body: MyAppsCircularProgressIndicator(title: "MyApp",),
);
}
},
);
}
}
this code works fine for connectionstate.
I would like to add in the first code:
if (not signed in) {
show sign in page
} else {
if (not registered)
show register page
else
show home page
}
or
StreamBuilder(
stream: auth.authStateChanges()
builder: (_, snapshot) {
// check connectionState too
if (snapshot.hasData) {
StreamBuilder(
stream: database.userData() // this is a stream you create that reads from `userData/$uid` or similar
builder: (_, snapshot) {
if (snapshot.hasData) {
return HomePage()
} else {
return RegisterPage()
}
}
)
} else {
return SignInPage()
}
}
)
I would like to add the last code to the previous one to have my connectionstate + my redirection to RegisterPage.
I tried everything but to no avail ... could someone help me? Thank you

Answer 1

You could use the provider package and then create a seperate file which has the following code. I personally use this and it works well.
class Wrapper extends StatelessWidget {
#override
Widget build(BuildContext context) {
final user = Provider.of<User>(context);
if (user == null) {
return SignIn();
} else {
return Dashboard();
}
}
}
and in your main.dart file where you are building the material app. Put the wrapper (or whatever you name it) widget instead such as the following.
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
#override
Widget build(BuildContext context) {
return FutureBuilder(
// Initialize FlutterFire
future: Firebase.initializeApp(),
builder: (context, snapshot) {
// Check for errors
if (snapshot.hasError) {
return ErrorPage();
}
// Show Application
if (snapshot.connectionState == ConnectionState.done) {
return StreamProvider<Help4YouUser>.value(
value: AuthService().user,
child: MaterialApp(
debugShowCheckedModeBanner: false,
home: Wrapper(),
),
);
}
// Initialization
return LoadingWidget();
},
);
}
}
Any clarification needed please comment