Question

The omniauth-facebook README mentions how to set it up in an initializer and how to set options like scope per request only. I wonder if it is possible to set app id and app secret per request as well.

Answer 1

You can do this:

On your omniauth.rb, do this:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :facebook,:setup => true
end

Then on your controller you have to define the following:

def setup
 request.env['omniauth.strategy'].options[:client_id] = @site.facebook_key
 request.env['omniauth.strategy'].options[:client_secret] = @site.facebook_secret
 render :text => "Setup complete.", :status => 404
end

Of course you have to add the associated routes, on your routes.rb.

  #Facebook Omniauth routes
  match '/auth/facebook/callback' => 'session#authorize_callback'
  match '/auth/facebook/setup' => 'session#setup'

Good luck

Regards.
Ivan.