在Flutter中使用Provider和FirebaseAuth将用户添加到状态

Question

我正在使用FirebaseAuth在Flutter应用程序中处理身份验证。但是，我还有其他要针对用户的信息，即组织和角色。这意味着我的数据库中有一个用户集合。我想根据用户是否登录来添加/删除用户。这是我当前的代码：

Main.dart

      providers: [
        StreamProvider<FirebaseUser>.value(
            value: FirebaseAuth.instance.onAuthStateChanged),
        ChangeNotifierProvider(
          create: (_) => UserProvider(),
        ),
      ],

Root.dart

  Widget build(BuildContext context) {
    var user = Provider.of<FirebaseUser>(context);

    bool isLoggedIn = user != null;

    if (isLoggedIn) {
      return HomeScreen(userId: user.uid);
    } else {
      return AuthScreen();
    }
  }

user_model.dart

enum Role { ADMIN, TUTOR, STUDENT }

class User {
  final String email;
  final String organisation;
  final Role role;

  User({this.email, this.organisation, this.role});

  factory User.fromMap(Map data) {
    getRole(String role) {
      switch (role) {
        case ('ADMIN'):
          return Role.ADMIN;
        case ('TUTOR'):
          return Role.TUTOR;
        case ('STUDENT'):
          return Role.STUDENT;
        default:
          return false;
      }
    }

    return User(
        email: data['email'] ?? '',
        organisation: data['organisation'] ?? '',
        role: getRole(data['role']));
  }

  Map<String, dynamic> toJson() {
    return {
      'email': email,
      'organisation': organisation,
      'role': role.toString().split('.').last
    };
  }
}

user_provider.dart

class UserProvider extends ChangeNotifier {
  User _user = User(email: '', organisation: '', role: null);

  User get user {
    return _user;
  }

  setUser(User user) {
    _user = user;

    notifyListeners();
    print("_USER: ${user.toJson()}");
  }

  clearUser() {
    _user = User(email: '', organisation: '', role: null);
  }
}

database_service.dart

  Future<User> getUser(String userID) {
    return _db
        .collection('users')
        .document(userID)
        .get()
        .then((user) => User.fromMap(user.data));
  }