Flutter Riverpod redirection after entity creation

Question

I'm working on my Flutter app and I try to set up a redirection process after creating an entity (user). The state management is handled by Riverpod. I'm using Firebase for the auth and Postgres for the database.

The insert method in the repository returns a User. With a StateNotifier I just want to check if the method returns a user. If the user is returned I set a success state object (CreateAccountStateSuccess), if it's not I set an error state object with a message. Problem: my saveUser method always return null in my StateNotifier, even though my user is persisted in Firebase and my database. I think it's a Riverpod issue. Any idea?

My repository:

  Future saveUser(String email, String nickname, String role,
      String firstname, String lastname) async {
    try {
      connection.open().then((value) async {
        Future>>> result = connection.mappedResultsQuery(
          'insert into public.user(email,nickname,role,firstname,lastname) '
          'values(@emailValue,@nicknameValue,@roleValue,@firstnameValue,@lastnameValue) '
          'returning *',
          substitutionValues: {
            'emailValue': email,
            'nicknameValue': nickname,
            'roleValue': role,
            'firstnameValue': firstname,
            'lastnameValue': lastname,
          },
          allowReuse: true,
          timeoutInSeconds: 30,
        );
        result.then((value) {
          final userFromDataBase = value[0]['user']!;
          return AppUser(
              email: userFromDataBase['email'],
              nickname: userFromDataBase['nickname'],
              role: userFromDataBase['role'],
              firstname: userFromDataBase['firstname'],
              lastname: userFromDataBase['lastname']
          );
        });
      });
    } catch (e) {
      print(ErrorHandler(message: e.toString()));
      return null;
    }
    return null;
  }

My Firebase method to create user for Firebase and using my repository method:

  Future registerWithEmailAndPassword(String email, String password, String nickname, String role, String firstname, String lastname) async {
    FirebaseApp app = await Firebase.initializeApp(
        name: 'Secondary', options: Firebase.app().options);
    try {
      UserCredential result =
      await FirebaseAuth.instanceFor(app: app).createUserWithEmailAndPassword(email: email, password: password);
      User? user = result.user;
      if (user == null) {
        throw Exception("No user found");
      } else {
        try {
          return await UserRepository(user.email!).saveUser(email, nickname, role, firstname, lastname);
        } on PostgreSQLException catch (e) {
          print('CATCH POSTGRES EXCEPTION');
          print(ErrorHandler(message: e.code.toString()));
        }
      }
    } on FirebaseException catch (e) {
      print('CATCH FIREBASE EXCEPTION');
      print(ErrorHandler(message: e.code.toString()));
    }
    return null;
  }

My controller:

class CreateAccountController extends StateNotifier {
  CreateAccountController(this.ref) : super(const CreateAccountStateInitial());

  final Ref ref;

  void register(String email, String password, String nickname, String role, String firstname, String lastname) async {
    state = const CreateAccountStateLoading();
    try {
      await ref.read(authRepositoryProvider).registerWithEmailAndPassword(
        email,
        password,
        nickname,
        role,
        firstname,
        lastname
      ).then((user){
        user != null ? state = const CreateAccountStateSuccess() : state = const CreateAccountStateError('Something went wrong with the user creation in database');
      });
    } catch (e) {
      state = CreateAccountStateError(e.toString());
    }
  }
}

final createAccountControllerProvider =
StateNotifierProvider((ref) {
  return CreateAccountController(ref);
});

My state objects :

class CreateAccountState extends Equatable {
  const CreateAccountState();

  @override
  List

user_2828341 · Answer

The problem is in the saveUser function. Instead of using .then use await. It would be like the following:

Future saveUser(String email, String nickname, String role,
    String firstname, String lastname) async {
  try {
    await connection.open();
    final result = await connection.mappedResultsQuery(
      'insert into public.user(email,nickname,role,firstname,lastname) '
      'values(@emailValue,@nicknameValue,@roleValue,@firstnameValue,@lastnameValue) '
      'returning *',
      substitutionValues: {
        'emailValue': email,
        'nicknameValue': nickname,
        'roleValue': role,
        'firstnameValue': firstname,
        'lastnameValue': lastname,
      },
      allowReuse: true,
      timeoutInSeconds: 30,
    );

    final userFromDataBase = result[0]['user']!;
    return AppUser(
      email: userFromDataBase['email'],
      nickname: userFromDataBase['nickname'],
      role: userFromDataBase['role'],
      firstname: userFromDataBase['firstname'],
      lastname: userFromDataBase['lastname'],
    );
  } catch (e) {
    print(ErrorHandler(message: e.toString()));
    return null;
  }
}

Flutter Riverpod redirection after entity creation

1 Answers