Using omniauth to facebook connect existing user with different permissions

Question

I'm using devise/omniauth to do facebook authentication and works great. However, I would like to add a flow where an existing (non-facebook) user has ability to connect his account with facebook. This would require different facebook permissions. so i can't seem to find two things

1. how to use devise/omniauth to request facebook connect without logging out current user
2. request different extended permissions from user (different from those specified in the devise configuration file)

any ideas? thanks

Answer 1

Answer to 1 is pretty easy: just add a if path into the omniauth_callbacks_controller::process_callback method like this

  # If a user is signed in then he is trying to link a new account
    if user_signed_in?
      if authentication.persisted? # This was a linking operation so send back the user to the account edit page  
        flash[:success] = I18n.t "controllers.omniauth_callbacks.process_callback.success.link_account", 
                                :provider => registration_hash[:provider].capitalize, 
                                :account => registration_hash[:email]
      else
        flash[:error] = I18n.t "controllers.omniauth_callbacks.process_callback.error.link_account", 
                               :provider => registration_hash[:provider].capitalize, 
                               :account => registration_hash[:email],
                               :errors =>authentication.errors
      end  
      redirect_to edit_user_account_path(current_user)

This is what I do in my application and it works fine.

Regarding question 2 I do not know how to support 2 different facebook authentication configurations however I have hard time seeing how that is useful to users since they need a consistent experience across both path: "sign in using facebook" and "link your account to facebook". (If you still want to pursue this path one idea I would explore is to create a new facebook application with its independent keys and configuration...)

Hope this help.