running interstitial step before creating an user
I'm trying to create a sso-oauth plugin for my site. the problem is my forum already has users and I don't want to create a new user for them when they register with this provider, but the OAuth provider does not return an email in user's profile, so I can't check if the request is for a new user or an existing one.
Now I'm trying to add an interstitial step to get the email from users when they register with my plugin. but I only managed to ask the users their email after creating a new user which is not ideal.
Is there a way to ask users additional information before creating a user?