ensure_uri.rb

class ApplicationController < ActionController::Base

  # ...
  ########################
  #     URL REDIRECTS    #
  ########################

  # Use this method to make sure that each page can only be accessed
  # by one URI. Will return false if a redirect has occured.
  # Example (in controller)
  #   ensure_uri production_path(@production) or return

  def ensure_uri(uri)
    #These session variable just help us keep out of infinite loops.
    unless session[:redirect_uri] == uri
      session[:redirect_count]=0
      session[:redirect_uri] = uri
    end

    if uri != request.request_uri && session[:redirect_count]<2
      # Bad URI, need to redirect.
      redirect_to uri, :status=>:moved_permanently 
      session[:redirect_count] += 1
      logger.info "Redirect for #{uri}: no. #{session[:redirect_count]}"
      flash[:notice]= CGI.escapeHTML("You have been redirected from #{request.env["HTTP_HOST"]}#{request.request_uri} to this page's new location.")
      false
    else
      # Landed at the right URI, with or without help from redirects.
      session[:redirect_uri]=''
      if session[:redirect_count] >= 2
        logger.warn "Too many redirects for #{uri}!!! Giving up on pretty URL with #{request.request_uri}"
      end
      true
    end
  end  
end