Firebase Phone Authentication credentials linking with Google login in firebase

Question

I have implemented two step authentication in my app using firebase authentication in which I have used gmail, facebook or simple email login for authenticating. As digits phone verification has migrated to firebase i have implemented firebase phone authentication by linking the existing logged in account (facebook, gmail, or email) with phone authentication credentials. It works fine when used with facebook and email account. When user is logged in through google and tries to verify mobile through phone authentication this logs are printed :

signInWithCredential:failure

com.google.firebase.auth.FirebaseAuthUserCollisionException: An account already exists with the same email address but different sign-in credentials. Sign in using a provider associated with this email address.

Read this article. Is it the same issue as mentioned in the article?? Is there any solution for the same..

Answer 1

After research over internet and in firebase documentation itself I found solution to this two step authentication in app using firebase auth.

firebaseAuth.getCurrentUser().updatePhoneNumber(credential).addOnCompleteListener(this, new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {
            if (task.isSuccessful()) {
                Log.d(TAG, "signInWithCredential:success");

                Snackbar.make(findViewById(android.R.id.content), "Mobile Verified Successfully.",
                        Snackbar.LENGTH_SHORT).show();

            } else {
                Log.w(TAG, "signInWithCredential:failure", task.getException());
                if (task.getException() instanceof FirebaseAuthInvalidCredentialsException) {
                    //mVerificationField.setError("Invalid code.");
                    Snackbar.make(findViewById(android.R.id.content), "Invalid Code.",
                            Snackbar.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(context,"signInWithCredential:failure"+task.getException(),
                            Snackbar.LENGTH_LONG).show();
                }
            }
        }
    });

Just pass the PhoneAuthCredential to above method and it will verify the phone assigns to your existing account. Make sure it is not used by any other account.

PhoneAuthCredential credential = PhoneAuthProvider.getCredential(verificationId, code);