Android FirebaseUI Auth: Upgrade From Anonymous Account to Permanent Account

October 14, 2019

Assuming you are using firebase-ui-auth for handle signin flow, you can easy convert anonymous account to permanent account (new permanent account will share same uid as anonymouse account).

fun getAuthIntent(): Intent {
    val currentUser = FirebaseAuth.getInstance().currentUser
    val providers = if (currentUser == null) {
        arrayListOf(
            AuthUI.IdpConfig.GoogleBuilder().build(),
            // AuthUI.IdpConfig.EmailBuilder().build(),
            AuthUI.IdpConfig.AnonymousBuilder().build()
        )
    } else { // remove anonymous if already sign in
        arrayListOf(
            AuthUI.IdpConfig.GoogleBuilder().build()
        )
    }

    val intent = AuthUI.getInstance()
        .createSignInIntentBuilder()
        .setAvailableProviders(providers)
        // if current user is anonymous, the new signin will have the same uid
        // if the signin is an existing user, a conflict will happen
        .enableAnonymousUsersAutoUpgrade()
        .build()
    startActivityForResult(intent, REQUEST_SIGN_IN)
}
class TestFragment : Fragment() {
    companion object {
        private const val REQUEST_SIGN_IN = 1
    }


    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)

        if (requestCode == REQUEST_SIGN_IN) {
            val response = IdpResponse.fromResultIntent(data)

            if (resultCode == RESULT_OK) {
                val user = FirebaseAuth.getInstance().currentUser
                if (user != null) {
                    Timber.d("name=${user.displayName}, email=${user.email}, uid=${user.uid}")
                }
            }
            else {
                response?.also { response ->
                    // when the signin credential is not a new user, while current user is anonymous
                    // as existing user cannot be linked to existing anonymous user
                    if (response.error?.errorCode == ErrorCodes.ANONYMOUS_UPGRADE_MERGE_CONFLICT) {
                        val currentAnonymousUser = FirebaseAuth.getInstance().currentUser
                        // TODO: save anonymous data


                        val newCredential = response.credentialForLinking
                        if (newCredential != null) {
                            FirebaseAuth.getInstance().signInWithCredential(newCredential)
                                .addOnSuccessListener {
                                    val newUser = FirebaseAuth.getInstance().currentUser
                                    // TODO: migrate/merge anonymous data to existing user
                                }
                        }

                    }
                    else {
                        Timber.e("REQUEST_SIGN_IN error", response.error)
                    }
                }
            }
        }
    }
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