Flutter Androit | Firebase Authentication Persistance with Firestore - firebase

Question

I wan't to persist authentication state of an user registered in Firebase Auth. The user has data in Firestore DB.
My final attempt :
main.dart
#override
Widget build(BuildContext context) {
return StreamProvider<AppUser?>.value(
value: AuthenticationService().user,
initialData: null,
child: const ....
);
}
home.dart
#override
Widget build(BuildContext context) {
var user = Provider.of<AppUser?>(context);
print(user);
Home.user = user;
...
}
authentication.dart
class AuthenticationService {
final FirebaseAuth _auth = FirebaseAuth.instance;
final FirebaseFirestore _db = FirebaseFirestore.instance;
final CollectionReference _usersCollection = FirebaseFirestore.instance.collection('users');
Stream<AppUser?> get user {
return _auth.authStateChanges().map((firebaseUser) {
AppUser? user;
_usersCollection.doc(firebaseUser!.uid).get().then((DocumentSnapshot userSnapshot) {
user = _toAppUser(firebaseUser, userSnapshot);
});
return user;
});
}
}
But with this code, the get user is always null, even just afte logging in

Answer 1

So after dozens of changes, the following code is "working" :
main.dart
#override
Widget build(BuildContext context) {
cart.cache();
return const MaterialApp(
title: 'CharleMi\'App',
debugShowCheckedModeBanner: false,
home: Home(),
);
}
home.dart
#override
Widget build(BuildContext context) {
return StreamBuilder<User?>(
stream: FirebaseAuth.instance.authStateChanges(),
builder: (context, snapshot) {
if (snapshot.hasData) {
AuthenticationService.delegate(snapshot.data).then((user) {
if (user != null) {
Home.user = user;
}
});
} else if (snapshot.hasError) {
print(snapshot.error);
}
return ....
authentication.dart
static Future<AppUser?> delegate(User? data) async {
return AuthenticationService()._toAsyncAppUser(data, null);
}
Future<AppUser?> _toAsyncAppUser(User? user) async {
AppUser _user = AppUser(uid: user!.uid);
var exists = await _user.init(); //Return true, get vars from firestore
if (exists) {
return _user; //Returned here when logging in (because exists)
}
return null;
}