Linking another provider to a Phone Auth account using email

Question

I am trying to prevent users from creating multiple accounts.

Specifically, I want to check if a user currently signing in with a non-Phone Auth method (Facebook, Google, etc.) has previously signed in via Phone Auth.

When creating a Phone Auth account I require that a user enters an email address. Once the user is created I save the email address to their authUser account using:

authData.user.updateEmail(to: email, completion: { (error) in
                // email added successfully
            })

The email address is saved correctly and is visible in the Firebase Authentication Console.

However, when I try to find providers for that email address later, using:

Auth.auth().fetchProviders(forEmail: email, completion: { (providers, error) in
                // providers.count = 0
            })

or

Auth.auth().fetchSignInMethods(forEmail: email, completion: { (signInMethods, error) in
                // signInMethods == nil
            })

The email isn't found.

So it appears that the email is connected to the User but not a provider or sign in method.

Is it possible to connect the email to the Phone Auth provider data so the email is found when looking for multiple accounts? Is there another way to skin this cat without having to query Firestore? I want to prevent logged out users from accessing documents.

bojeil bojeil · Accepted Answer · 2019-04-15T06:33:04

fetchSignInMethods will not return any results even if the email exists but has no providers or sign-in methods to sign in with.

In your case, you just update the email or an account. That is not enough. The user has to sign in with the email. For example, if the user signs with email link or password, then fetchSignInMethods will return these methods of sign-in.

Linking another provider to a Phone Auth account using email

1 Answers