Firebase UI Auth (ProfileScreen) detect when a user updates their Display Name

I'm using the firebase_ui_auth package to control auth and my ProfileScreen. I'm building a Flutter app using Firestore/Firebase Auth. When the user account is created I have a Cloud Function trigger to create a user document users/${uid}.

What I want to happen is when a user updates their Display Name that the update syncs with Firestore. I have a Provider (Riverpod) that listens to AuthStateChanges, however, updating a user doesn't trigger that.

There are no Cloud Functions for this kind of trigger.

How can I listen for these kinds of changes (and get the actual change)? I can easily update Firestore once I understand where to listen for changes

You can use userChanges method which will listen for any changes in user profile, So you can update the displayName accordingly as follows :

import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

void listenForUserProfileChanges() {
  FirebaseAuth.instance.userChanges().listen((User? user) async {
    if (user != null) {
      String newDisplayName = user.displayName ?? '';
      String uid = user.uid;

      try {
        // Update the displayName in the Firestore document
        await FirebaseFirestore.instance
            .collection('users')
            .doc(uid)
            .update({'displayName': newDisplayName});
        print('DisplayName updated successfully in Firestore document.');
      } catch (error) {
        print('Error updating DisplayName in Firestore: $error');
      }

      print('User $uid updated their displayName to $newDisplayName');
    } else {
      print('User is null');
    }
  });
}

void main() {
  listenForUserProfileChanges();
}

I have wrapped this into a function but you can specify anywhere in your application.

Reference : userChanges method