State managment in flutter with consumer and scaffoldState - flutter

Question

I'm using the Provider dependencie to manage states on my screen. Currently I have created a Loading Screen that works with Lottie animation. In my Sign In page, whenever there is an error with the log in, a Snackbar is shown to the user. Althought now, when I use the splash screen, the screen doesn't return and the snackBar isn't shown.
This is a piece of the login screen:
Padding(
padding: const EdgeInsets.only(top: 20.0),
child: RaisedButton(
onPressed: userManager.loading
? null
: () {
if (formKey.currentState!
.validate()) {
userManager.signIn(
user: User(
email:
emailController.text,
password:
passController.text),
onFail: (e) {
scaffoldKey.currentState!
.showSnackBar(SnackBar(
content: Text(
'Falha ao entrar: $e'),
backgroundColor:
Colors.red,
));
},
onSucess: () {
debugPrint(
'Sucesso ao Logar');
Navigator.of(context).pop();
});
}
},
On the onFail I get this error, whenever I have a wrong password or other datas wrong:
Ocorreu uma exceção.
_CastError (Null check operator used on a null value)
This is how I'm changing between pages:
class LoginScreen extends StatelessWidget {
final GlobalKey<FormState> formKey = GlobalKey<FormState>();
final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
final TextEditingController emailController = TextEditingController();
final TextEditingController passController = TextEditingController();
#override
Widget build(BuildContext context) {
return Consumer<UserManager>(builder: (_, userManager, child) {
if (userManager.loading) {
return SplashScreen();
} else {
return Scaffold(
key: scaffoldKey,
appBar: AppBar(
UserManager:
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/services.dart';
import 'package:loja_virtual_nnananene/helpers/firebase_errors.dart';
import 'package:loja_virtual_nnananene/models/user.dart';
class UserManager extends ChangeNotifier {
UserManager() {
_loadCurrentUser();
}
final FirebaseAuth auth = FirebaseAuth.instance;
User? user;
bool _loading = false;
bool get loading => _loading;
bool get isLoggedIn => user != null;
Future<void> signIn(
{required User user,
required Function onFail,
required Function onSucess}) async {
loading = true;
try {
final AuthResult result = await auth.signInWithEmailAndPassword(
email: user.email!, password: user.password!);
await _loadCurrentUser(firebaseUser: result.user);
onSucess();
} on PlatformException catch (e) {
onFail(getErrorString(e.code));
}
loading = false;
notifyListeners();
}
Future<void> signUp(
{required User user,
required Function onFail,
required Function onSucess}) async {
loading = true;
try {
final AuthResult result = await auth.createUserWithEmailAndPassword(
email: user.email!, password: user.password!);
user.id = result.user.uid;
this.user = user;
await user.saveData();
onSucess();
} on PlatformException catch (e) {
onFail(getErrorString(e.code));
}
loading = false;
notifyListeners();
}
void signOut() {
auth.signOut();
user = null;
notifyListeners();
}
set loading(bool value) {
_loading = value;
notifyListeners();
}
Future<void> _loadCurrentUser({FirebaseUser? firebaseUser}) async {
final FirebaseUser currentUser = firebaseUser ?? await auth.currentUser();
if (currentUser != null) {
final DocumentSnapshot docUser = await Firestore.instance
.collection('users')
.document(currentUser.uid)
.get();
user = User.fromDocument(docUser);
final docAdmin = await Firestore.instance
.collection('admins')
.document(user!.id!)
.get();
if (docAdmin.exists) {
user!.admin = true;
}
notifyListeners();
}
}
bool get adminEnabled => user != null && user!.admin;
}
Is there another way to set the splash screen thats easier?

Answer 1

While I wait for you to add the UserManager class implementation, I think there's a missing notifyListeners() in the signIn method.