gistfile1.rb

Rails.configuration.middleware.use Warden::Manager do |manager|

  manager.failure_app = SessionsController
    
  manager.serialize_into_session do |user|
    user.id.to_s
  end

  manager.serialize_from_session do |id|
    User.first( :conditions => { :id => id } )
  end

  Warden::Manager.before_failure do |env, opts|
    request = env[ "action_controller.rescue.request" ] ||= ActionController::Request.new( env )
    env[ 'action_dispatch.request.path_parameters' ][ :action ] = "unauthenticated"
  end

  Warden::Strategies.add :facebook do

    def valid?
      request.cookies && request.cookies[ "fb_access_token" ]
    end

    def authenticate!
      u = User.first :conditions => { :fb_access_token => request.cookies[ "fb_access_token" ] }
      u.nil? ? throw( :warden ) : success!( u )
    end

  end

end