Devise / Omniauth - 如何处理不包含电子邮件的提供商

I have a Rails app that uses Devise and Omniauth to handle authentications. As prescribed I am receiving callbacks from the providers in my omniauth_callbacks_controller, where I check if the authentication already exists, and whether a user with the email given by the provider already exists, creating a new user if necessary. I have a Rails app that uses Devise and Omniaut