Firebase-js-sdk: Are there anyway that we could used to check that the credential existed but not create new account?

[Thaina]

Since we could get and link credential with many sources. Google, Facebook, GooglePlay, GameCenter, github, etc. I need to have some way to verified that, is the credential already existed and linked with some ID or not

But I don't want to signed in with that credential immediately. Because I need to generate custom userID. If it linked I will let it signed it. But if it not I would like to have user pass the initial process first and the server will minting the token to let user signing in and link their credential with it after that

Is there any API to do that, especially in client?

If not I would like to request API Auth.getUserIDFromCredential(credential) or Auth.signInWithExistingCredential(credential) that will signed in only if the credential has already been linked with any account

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[hiranya911]

Authentication and account linking are all client-side APIs. I think this should be reported in the JS SDK repo.

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[Thaina]

@hiranya911 This functionality could be useful in both client and server side. And if it has this function in server side, client side could proxy it around this time

Also if logic would required server side to check the existence of 3rd party access token. Server side could do so

Please move this back to node repo

[bojeil-google]

There is no API to do so. Feel free to file an official feature request for it. It is unlikely to be supported but we have plans to provide an admin sdk API to lookup by federated ID. So if you have the Facebook user ID, you can lookup if the user exists in the Auth database.

[Thaina]

@bojeil-google

we have plans to provide an admin sdk API to lookup by federated ID

I was request that functionality for such years and it's not exist yet

But still I wish that atleast the google auth server could have some endpoint, like verifyAssertion, that could specify parameter to actually only verify the token but not create new account just yet

It's too weird that we didn't have this functionality available anywhere at all. It just so common when we could link any ID with credential, we should have some way to check that this credential was not linked with anything yet

Actually I was expect that
from this doc https://firebase.google.com/docs/reference/rest/auth#section-sign-in-with-oauth-credential
I should call relyingparty/verifyAssertion with "returnSecureToken":false and then it will not try to create user, return empty userID if not exist. Or something like that

[Thaina]

@bojeil-google Hello are there any update on this?

[Thaina]

@bojeil-google @MeghaB As of now we have getUsers in Admin SDK. Are there any chance it would be exposed in client SDK ?

In my use case it could just return object as UserInfo instead of full UserRecord. But it should be allowed to be called from client directly. Or else I need to made cloud function for call it anyway

Actually I wish that it would be the same API. But if it called from client directly then it could be call as anonymous, only return some field (maybe just ID,name,photoURL) and would have lower limit of number it could request (is 30 possible ?)

And firebase server could limit client spamming on this API too

In this way it also useful for social multiplayer game that user could get a friend list (such as from facebook) and then they could get firebaseID to do other thing directly from client side

[malcolmdeck]

Hey Thaina,

I've filed b/169068814 to track this feature request internally. If you want to be able to solve this problem right now, you can upgrade your project to Identity Platform (the enterprise offering of Firebase Authentication) and disable client signup. Other than that, you can just use a Cloud Function and the Admin SDK like you've suggested.

Hope that helps!
~Malcolm

[Thaina]

Thank you very much