How to set username on OAuth signup?

I have

disableImplicitSignUp

disableImplicitSignUp

disableImplicitSignUp

disableImplicitSignUp enabled and want users to choose a username before signing up with OAuth.

Here’s the flow I’m aiming for:

User clicks "Sign in with Google"
A dialog appears before redirecting to Google, asking for:
A username
Agreement to Terms of Service, etc.

After submission:

If the user already exists → proceed to sign in via Google
If the user doesn't exist → store the username and proceed to Google
- After Google redirects back → create the account using the previously provided username

Note: I’m aware I can do this after with

newUserCallbackUrl = "/complete-signup"

newUserCallbackUrl = "/complete-signup"

newUserCallbackUrl = "/complete-signup"

newUserCallbackUrl = "/complete-signup",but I want this step to happen before the Google sign-in redirect.
Is this possible?

FalconiZzare•6/29/25, 5:24 AM

You may look into before and after hooks.

FalconiZzare•6/29/25, 5:24 AM

https://www.better-auth.com/docs/concepts/hooks

Hooks | Better Auth

Better Auth Hooks let you customize BetterAuth's behavior

Omar-7iooOP•6/29/25, 10:15 AM

Thanks Falcon, I actually played with it but here is the issue that I faced.

I could pass a body:{username}body:{username} to the

/sign-in

/sign-in

endpoint but how would I pass that to /callback/:id/callback/:id?

I can change the response of

/sign-in

/sign-in

but can I make

/sign-in

/sign-in

pass more data to /callback/:id/callback/:id?

Assuming i was able to pass it to /callback/:id/callback/:id the user creation comes after this /cabllack/:id/cabllack/:id, so how can I create a user with username?

OOmar-7ioo Thanks Falcon, I actually played with it but here is the issue that I faced. I ...

FalconiZzare•6/29/25, 10:23 AM

I see the issue u r facing. I don't have an answer for this right now until I try it myself.
However people were using some workarounds like setting a bool in user profile whether they have completed username choosing stage or not, if not force redirect them to username choosing page after sign in/sign up.

But that's a bit too much for this, you can look around the discord server for a solution which handles this within one flow. I remember people facing the same issue.

Omar-7iooOP•6/29/25, 10:45 AM

Great thanks. I took a look at GitHub, it looks like there is a pr and a feature request for signUp flows on OAuth.

Sadly not implemented yet. I'll see if there is no workaround I'm thinking of wrapping my head around the library and making a pr

OOmar-7ioo Great thanks. I took a look at GitHub, it looks like there is a pr and a feature...

FalconiZzare•6/29/25, 7:16 PM

Cool. Make sure to tag becka or ping

How to set username on OAuth signup?

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