A thin wrapper around the Rails ‘flash’ object, to assist in redirecting a user ‘back’ to the page she originally requested.

For more info see the AuthenticationNeededSan class documentation.

Consider an application which uses the authorization-san plugin. The ApplicationController would look something like the following:

class ApplicationController < ActionController::Base
  # If nobody was logged in and this resource is not accessable by all,
  # request authentication. Otherwise reply that the resource is forbidden.
  def access_forbidden
    # If the user is logged in and still can't view the page, we have to tell
    # them access is forbidden.
    if !@authenticated.nil?
      send_response_document :forbidden
    else
      authentication_needed!
    end
  end

  def when_authentication_needed
    redirect_to new_session_url
  end
end

Then from your sessions controller redirect the user back to the page she requested or the default one:

class SessionsController < ApplicationController
  def create
    # login code...
    finish_authentication_needed! or redirect_to(root_url)
  end
end

The authorization-san plugin is available at: github.com/Fingertips/authorization-san