notifyListeners in flutter not working, i.e. the value is not at all updated

Question

below is the code where for my UserProvider. The commented line in it is for the testing purpose and when it was used, I got the username as "test" in output on screen.

class UserProvider with ChangeNotifier {
  // UserModel _user = UserModel(username: "test", isLoggedIn: false, isVerified: false);
  UserModel _user;

  setUser(UserModel user) 
  {
    _user = user;
    notifyListeners();
    print("user data changed !");
  } 

  UserModel get getUser => _user;
}

Below is How I am updating data via a api call:

UserProvider().setUser(
                UserModel(
                username: user['username'] ?? 'Guest', 
                email: user['id'] != null ? user['email'] : 'not available', 
                avatar: user['id'] != null ? user['avatar'] : 'not available',
                ),
              ); 

there are not error in runtime and I have a line in the setUser method which is there to check if the method was called or not print("user data changed !"). and in terminal I do get this line out put, so the function is not skipped and definitely called.

on screen I am calling the data as below:

UserModel user;

  @override
  void didChangeDependencies() {
    user = Provider.of<UserProvider>(context).getUser;
    super.didChangeDependencies();
  }

and

Text("Hi, ${user.username}"),

Output is not the new data. its either NULL if the commented line is not used, and if used, the username is test.

So where am I going wrong?

All help is appreciated.

Thank you for going through my question.

Solution

Regarding this line of codes in your question

UserProvider().setUser(
            UserModel(
            username: user['username'] ?? 'Guest', 
            email: user['id'] != null ? user['email'] : 'not available', 
            avatar: user['id'] != null ? user['avatar'] : 'not available',
            ),
          ); 

where are you using it?, because it seems it creates new UserProvider() everytime when it is called...

Make sure it's called from the right place something like shown in official docs here https://flutter.dev/docs/development/data-and-backend/state-mgmt/simple

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (context) => UserProvider(),
      child: MyApp(),
    ),
  );
}

Comments

[princeoo7]

any update for me on the? as of now I am using the value from the general API. if the question is not answered, I will need to make multiple call for the small data on splash screen.