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I am using the Firebase authentication functionality. I am using Facebook, Google, Twitter and email and password as providers. The default functionality is to use a single email by authentication.

If I authenticate with an account with Facebook, Twitter or Google and then try to enter but using email and password to do it, it shows me a warning where it says that I already use another authentication method and it allows me to do it with the previous one.

If I authenticate with email and password and then try to authenticate with Google, Twitter or Facebook these authentication methods overlap, that is, take both and in the Firebase console I can see that they are both.

Now, if I authenticate with email and password, Facebook (I think) or Twitter and then try to authenticate with Google, it deletes the previous authentication methods. That is, if with the first authentication methods I had id1 after authenticating with Google, the entry with id1 is deleted and one is created with id2.

This generates a problem in my application because it is a way to lose the user's registry previously created with id1.

I'm not sure if this is the expected behavior but I do not think so. Obviously whenever I refer to doing a 'new authentication' with another method I make sure to use the same email.

KENdi
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Alexander Sandoval Figueredo
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2 Answers2

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It sounds like you are looking for account-linking. This is possible in Firebase-authentication. Users are identified by their Firebase Userid and you can link multiple authentication providers to a userid.

Try to check this documentation. I think this is what you are looking for: https://firebase.google.com/docs/auth/web/account-linking

I hope it helps.

dsjacobsen
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The Google provider overwriting the existing providers is due to Google emails being verified as Google owns these email addresses.

To work around this, you will need to verify the email after the user signs up by sending an email verification. This guarantees that Google sign-in will not unlink the providers as the email is considered to be verified. So if a user signs up with Facebook (using a Google email), verify the email so next time the user signs in with the same Google email, the Facebook provider would remain on the user.

bojeil
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