app/controllers/users/omniauth_callbacks_controller.rb
class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
def facebook
@user = User.find_for_facebook_oauth(request.env["omniauth.auth"], current_user)
sign_in @user
if @user.created_at < 2.minutes.ago
redirect_to "/"
else
redirect_to "/onboarding/start"
end
end
end