Firebase 用户的显示名称在注册后没有更新。 我需要重新启动应用程序才能使其正常工作

Question

I want the firebase user's displayName to update as soon as it registers so that I can display the first letter of their name in a drawer. After I register the user with displayName and open the profile drawer it shows an error saying that displayName[0] is null but as soon as I restart the app can recognize the user. How do I make the app recognize the user's name after registration?

Authentication code

class AuthService {
  final FirebaseAuth _auth = FirebaseAuth.instance;

  UserModel? _userFromFirebaseUser(User? user) {
    return user != null
        ? UserModel(
            uid: user.uid,
            email: user.email ?? '',
            displayName: user.displayName ?? '',
          )
        : null;
  }


  Future signInWithEmailAndPassword(String email, String password) async {
    try {
      UserCredential result = await _auth.signInWithEmailAndPassword(
        email: email,
        password: password,
      );
      User user = result.user!;
      return user;
    } catch (error) {
      return null;
    }
  }
}

Register Page

  final AuthService _auth = AuthService();
  final _formKey = GlobalKey<FormState>();
  bool isLoading = false;

  String email = '';
  String password = '';
  String name = '';
  String error = '';

  void register(String email, String password, String name) async {
    if (_formKey.currentState!.validate()) {
      setState(() => isLoading = true);
      dynamic result = await _auth.registerWithEmailAndPassword(email, password, name);

      if (result == null) {
        setState(() => isLoading = false);
        setState(() => error = 'Please supply a valid email');
      }
    }
  }

Widget where the name is diplayed

    Widget build(BuildContext context) {
    final user = Provider.of<UserModel?>(context);

    String? displayName = user!.displayName;
    String profileDisplayName = user.displayName[0];

    .
    .
    .

    CircleAvatar(
        radius: 50,
        backgroundColor: Colors.orangeAccent,
        child: Center(
          child: Text(
             profileDisplayName,
             style: const TextStyle(
                fontSize: 50,
                color: Colors.white,
               ),
             ),
           ),
        ),
     const SizedBox(height: 10),
     Text(
       displayName,
       style: const TextStyle(
       fontSize: 20,
       color: Colors.white,
       letterSpacing: 0.6,
       ),
     ),

I tried to reload the app using initState() but that didn't work, I tried to user reload() function in the auth service but that didn't work either.

Answer 1

reload your user data and fetch again

class AuthService {
          final FirebaseAuth _auth = FirebaseAuth.instance;
        
          UserModel? _userFromFirebaseUser(User? user) {
            return user != null
                ? UserModel(
                    uid: user.uid,
                    email: user.email ?? '',
                    displayName: user.displayName ?? '',
                  )
                : null;
          }
        
        
          Future signInWithEmailAndPassword(String email, String password) async {
            try {
              UserCredential result = await _auth.signInWithEmailAndPassword(
                email: email,
                password: password,
              );
              User user = result.user!;
              await user.reload();
              user = await _auth.currentUser();
              return user;
            } catch (error) {
              return null;
            }
          }
        }