Flutter Firebase auth bloc return Firebase auth user and firestore datas in same stream

Question

I'm trying to handle firebase authentication and acces user datas from cloud firestore with BloC . I use the flutter firebase login tutorial from the bloc library. In this tutorial we can manipulate user authentication with firebase and get the auth User datas from the authStateChanges() and create a stream on changes. I would like to read datas from cloud firestore and add those datas to the same stream.

The original Stream from authentication_resposiroty.dart :

     /// Stream of [User] which will emit the current user when
      /// the authentication state changes.
      ///
      /// Emits [User.empty] if the user is not authenticated.
      Stream<User> get user {
        return _firebaseAuth.authStateChanges().map((firebaseUser) {
          print('User: $firebaseUser');
    
          final user = firebaseUser == null ? User.empty : firebaseUser.toUser;
          _cache.write(key: userCacheKey, value: user);
          return user;
        });
      }

extension on firebase_auth.User {
  User get toUser {
    return User(
      id: uid,
      email: email,
      photo: photoURL,
      emailVerified: emailVerified,
    );
  }
}

I try somethiing like that:

/// Stream of [User] which will emit the current user when
  /// the authentication state changes.
  ///
  /// Emits [User.empty] if the user is not authenticated.
  Stream<User> get user {
    return _firebaseAuth.authStateChanges().asyncExpand<User>((firebaseUser) {
      print('User: $firebaseUser');

      if (firebaseUser == null) {
        final user = User.empty;
        _cache.write(key: userCacheKey, value: user);
        print('User: firebaseUser == null :  $user');
        return Stream.value(user);
      } else {
        return _firebaseFirestore
            .collection('Users')
            .doc(firebaseUser.uid)
            .snapshots()
            .map((snapshot) {
          final user = User(
            id: firebaseUser.uid,
            email: firebaseUser.email,
            emailVerified: firebaseUser.emailVerified,
            datas: snapshot.data(),
          );
          _cache.write(key: userCacheKey, value: user);
          print('User: firebaseUser not null $user');
          return user;
        });
      }
    });
  }

This work, i can read my user datas from firestore and if I modify my datas drome firestore the update well, but I have some issues, when i try to login, the stream takes time and my redirection doesn't work because I check if the user.emailVerified is True, the stream is updated after my verification, I have to press my loggin button a second time... and then when I want to logout, I have then next error that I don't have before with the original code:

I/flutter (22885): AppLogoutRequested()
D/FirebaseAuth(22885): Notifying id token listeners about a sign-out event.
D/FirebaseAuth(22885): Notifying auth state listeners about a sign-out event.
W/Firestore(22885): (24.2.1) [Firestore]: Listen for Query(target=Query(Users/YyvBbHtujyNXZser92XfEfDSRqY2 order by __name__);limitType=LIMIT_TO_FIRST) failed: Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}
E/flutter (22885): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: [cloud_firestore/permission-denied] The caller does not have permission to execute the specified operation.
E/flutter (22885):

It looks like I'm not logged but I'm.

I start with flutter and bloc so sorry if it's not clear...

Thank you in advance for your answers.

Answer 1

If I understand correctly, the security rules of your Users collection require that a user is signed in to read the/their data.

It looks like your code successfully subscribes to the data in Firestore when the user signs in, which means you have a persistent listener checking for updates to that data.

But when the user signs out, the listener no longer meets the requirement of your security rules, so it gets canceled automatically by Firestore at that point. This is when you get the error message.

To prevent getting the error message, you can detach the listener before logging the user out. The.net result will be the same, but by detaching it on time you will not get the error message from the server.