Anonymous session id in rails

application_controller.rb

class ApplicationController < ActionController::Base
  def anonymous_id
    if !session.has_key? :session_id
      # LAME we have to write to the session to get it to initialize itself
      # the following line could be anything that writes to the session
      # except don't write to session_id, because that's what we need
      session[:id] = session[:id]
    end
    session[:session_id]
  end
end