Cannot set user display name in my flutter app - firebase

Question

I have been trying to set my user display name upon signup. All of the solution I have found in stackoverflow suggest to use updateProfile(). But it is deprecated, and flutter docs say to use updateDisplayName instead.
I have tried to implement it in this way,
void donorSignUp() async {
try {
showLoading();
await auth
.createUserWithEmailAndPassword(
email: email.text.trim(), password: password.text.trim())
.then((result) {
String _userId = result.user!.uid;
_addDonorToFirestore(_userId);
_clearSignUpControllers();
result.user?.updateDisplayName(donorModel.value.name);
});
} catch (e) {
debugPrint(e.toString());
Get.snackbar('Sign Up Failed', 'Try again');
}
}
However, when I try to show it in my Drawer, calling user?.displayName it doesn't show anything. I have also checked that donorModel.value.name consists a string value, I know its not null. What should I do?
the function donorSignUp() is called inside an elevatedbutton,
child: ElevatedButton(
child: Text(
'Register',
style: buttonFontSansita,
),
onPressed: () {
if (authController
.signupFormKey.currentState!
.validate()) {
authController.donorSignUp();
}
},

Answer 1

The recommended way to always have the real-time auth state is to use the authStateChanges listener:
FirebaseAuth.instance
.authStateChanges()
.listen((User? user) {
if (user == null) {
print('User is currently signed out!');
} else {
print('User is signed in!');
}
});
You can read more about it here. Ideally you can use a Provider to make the data available through the whole app.