gistfile1.rb

      def form_authenticity_token
        @form_authenticity_token ||= if !session.respond_to?(:session_id)
          raise InvalidAuthenticityToken, "Request Forgery Protection requires a valid session.  Use #allow_forgery_protection to disable it, or use a valid session."
        elsif request_forgery_protection_options[:secret]
          authenticity_token_from_session_id
        elsif session.respond_to?(:dbman) && session.dbman.respond_to?(:generate_digest)
          authenticity_token_from_cookie_session
        else
          raise InvalidAuthenticityToken, "No :secret given to the #protect_from_forgery call.  Set that or use a session store capable of generating its own keys (Cookie Session Store)."
        end
      end