Auth: How to solve user credential merge conflict?

[initfusion]

Hi,

Anyone can please help me to solve merge conflicts when link account.
How to link account when the credentials already have an existing account.

Thanks.

[cynthiajoan]

Hi @initfusion, you can start from this doc, which introduces how to link multiple auth providers to one account in Unity. You can also find related docs for other platforms under iOS / Android / Web and C++.

Hope this helps.

[initfusion]

Hi @cynthiajoan, this doc is not enough for solving conflicts. Because the credentials which I linking is having an existing account so we have to delete the new account first. After that, we can link.

I have followed the doc https://firebase.google.com/docs/auth/web/account-linking

// Get reference to the currently signed-in user
var prevUser = auth.currentUser;
// Sign in user with another account
auth.signInWithCredential(credential).then(function(user) {
  console.log("Sign In Success", user);
  var currentUser = user;
  // Merge prevUser and currentUser data stored in Firebase.
  // Note: How you handle this is specific to your application

  // After data is migrated delete the duplicate user
  return user.delete().then(function() {
    // Link the OAuth Credential to original account
    return prevUser.linkWithCredential(credential);
  }).then(function() {
    // Sign in with the newly linked credential
    return auth.signInWithCredential(credential);
  });
}).catch(function(error) {
  console.log("Sign In Error", error);
});

But the above code is in javascript.

In c# how to store prevUser? when I have signInWithCredantial I am lost the current user.

[cynthiajoan]

Hi @initfusion, if I understand correctly, in Unity/C#, we have this example maybe can solve your problem:
Unity account linking

// Gather data for the currently signed in User.
string currentUserId = auth.CurrentUser.UserId;
string currentEmail = auth.CurrentUser.Email;
string currentDisplayName = auth.CurrentUser.DisplayName;
System.Uri currentPhotoUrl = auth.CurrentUser.PhotoUrl;

// Sign in with the new credentials.
auth.SignInWithCredentialAsync(credential).ContinueWith(task => {
if (task.IsCanceled) {
Debug.LogError("SignInWithCredentialAsync was canceled.");
return;
}
if (task.IsFaulted) {
Debug.LogError("SignInWithCredentialAsync encountered an error: " + task.Exception);
return;
}

Firebase.Auth.FirebaseUser newUser = task.Result;
Debug.LogFormat("User signed in successfully: {0} ({1})",
newUser.DisplayName, newUser.UserId);

// TODO: Merge app specific details using the newUser and values from the
// previous user, saved above.
});

You can grab prevUser by auth.CurrentUser before signInWithCredantial.

Let me know if that works for you.

[initfusion]

Hi @cynthiajoan
Yes, I have done that way but after doing signInWithCredantial the prevUser which I have grabbed previously is also changed to the new user.

I think its sync new user to all its existing user instances.

[initfusion]

Hi
This is I am trying

        var credential = EmailAuthProvider.GetCredential(email, password);

        auth.CurrentUser.LinkWithCredentialAsync(credential).ContinueWithOnMainThread(task =>
        {
            if (task.IsCanceled)
            {
                Debug.Log("Cancel");
            }

            if (task.IsFaulted)
            {
                Debug.Log("Faulted");

                var currentUser = auth.CurrentUser;

                otherAuth.SignInWithCredentialAsync(credential).ContinueWithOnMainThread(linkTask =>
                {
                    Debug.Log("Current: " + currentUser.UserId);
                    Debug.Log("New: " + linkTask.Result.UserId);

                    // Here both current and new have the same user.
                });
            }

            if (task.IsCompleted)
            {
                Debug.Log("Completed");
            }
        });

[patm1987]

HI @initfusion ,

as per @cynthiajoan suggestion, have you tried caching the individual fields you need before executing the SignInWithCredentialAsync? The JavaScript and Unity APIs will be slightly different.

--Patrick

[initfusion]

Hi @patm1987,

Yes, I can cache the individual fields but I need the previous user to link the user.
Without a previous user, I can't call the LinkWithCredantials.

[patm1987]

With the Unity API, you just need the credential of the account you want to link with the current one (ie: if your continuation from LinkWithCredentialAsync succeeds, you should have linked accounts). You can get more information here:
https://firebase.google.com/docs/reference/unity/class/firebase/auth/firebase-user#linkandretrievedatawithcredentialasync

Let me know if it's not the case, but you should be able to verify that the merger worked in your firebase authentication dashboard (in console.firebase.google.com).

[initfusion]

Hi @patm1987

Yes, it's not the case, Link account is working properly when there is no error when link.
But if there is an error (ie: if the credential which is I am going to merge is already having an account).

In that case, I have to delete the existing account. for delete existing account I have to SignIn so I can get the user and using that user I can delete.

if there is another way to solve merge conflicts then let me know.

Let me know if you still not understand my problem.

[stewartmiles]

@initfusion it looks like you've found a problem with both the C++ and Unity SDKs here. You're right that it's not currently possible to copy the FirebaseUser object in the C# API which is an issue in the case you've described where you want to:

• Cache the current user's auth token
• Attempt to sign in with credentials (e.g email / password) and if that results in a different user, delete the other user's account.
• Link the credentials (email / password) with the current user's account

However, I think it's possible to do this with multiple FirebaseApp objects instead:

• Create a secondary FirebaseApp object and a FirebaseAuth object from that (e.g otherAuth)
• Then if credential linking fails with FirebaseAuth.DefaultInstance.CurrentUser, sign-in to otherAuth with the credentials
• Delete otherAuth.CurrentUser
• Try linking credentials on FirebaseAuth.DefaultInstance.CurrentUser again

[initfusion]

Hi @stewartmiles

Thanks for understanding my problem.
I was also tried with multiple Firebase objects but still not able to get or cache the current user's auth token.

Here is my code

otherAuth = FirebaseAuth.GetAuth(FirebaseApp.Create(AppOptions.LoadFromJsonConfig(conf.text)));

Now I am trying this but still, both are the same.

var credential = EmailAuthProvider.GetCredential(email, password);
  auth.CurrentUser.LinkAndRetrieveDataWithCredentialAsync(credential).ContinueWithOnMainThread(task =>
        {
            if (task.IsCanceled)
            {
                Debug.Log("Cancel");
            }

            if (task.IsFaulted)
            {
                Debug.Log("Faulted");
                
                otherAuth.SignInWithCredentialAsync(credential).ContinueWithOnMainThread(linkTask =>
                {
                    Debug.Log("Current: " + auth.CurrentUser.UserId);
                    Debug.Log("New: " + otherAuth.CurrentUser.UserId);

                    // Here both current and new have same user..
                });
            }

            if (task.IsCompleted)
            {
                Debug.Log("Completed");
            }
        });

[stewartmiles]

FirebaseApp.Create() will create the default app, you need to create a named secondary app using FirebaseApp.Create(options, name) see https://firebase.google.com/docs/reference/unity/class/firebase/firebase-app#class_firebase_1_1_firebase_app_1a39a702e1912ab6b708600b03bd955f4d

Here's an example:
https://github.com/firebase/quickstart-unity/blob/master/auth/testapp/Assets/Firebase/Sample/Auth/UIHandler.cs#L97