Caching in Rails

One can perform caching in rails on different levels

• page
• action
• page fragments
• model
• method

All these issues are covered by plugin cache_fu. Definitely you should look through presentation available on the plugin's page.

Caching in rails is covered to great extent in

• http://www.railsenvy.com
  • Ruby on Rails Caching Tutorial - Part 1
  • Ruby on Rails Caching Tutorial - Part 2
• http://errtheblog.com/posts/57-kickin-ass-w-cachefu
• and in
  • http://www.ibm.com/developerworks/web/library/wa-rails1/index.html?S_TACT=105AGX99&S_CMP=CP (translation to russian)
  • http://agilewebdevelopment.com/plugins/action_cache
  • http://www.igvita.com/2007/06/13/caching-and-mime-types-in-rails/
  • http://www.fucema.net/2007/8/28/mephisto-on-mongrel-cluster-nginx

The simple problem

I have to solve the following problem:

Cache pages/actions only for unauthorized users.

Existing solutions

There are some published solutions:

• http://www.ethelred.org/articles/2006/10/22/conditional-use-of-page-cache-in-rails
  • Caches total pages. Is done by caches_pages and configuring Apache.
• http://weblog.redlinesoftware.com/2007/11/26/conditional-cache-plugin-tutorial (conditional caching for caches_action)
  • caches actions. Allows to use option :if.
  • installed by ruby script/plugin install http://svn.redlinesoftware.com/plugins/conditional_cache/
• http://elctech.com/2007/6/20/conditional-action-caching-with-cache_fu
  • provides patch for starring cache_fu

My solution

A great many lines of code are written for implementing caching in rails. But I would like to add one more small chunk:

# Use this instead of caches_action
def caches_action_unless_auth(*actions)
  options = nil
  options = actions.pop if actions.last.is_a?(Hash)
  @@check_auth_count ||= 0
  before_method = "check_auth_methods_#{(@@check_auth_count += 1)}".to_sym
  self.class_eval do
    define_method(before_method) do
      if authenticated?
        self.action_name += '_auth'
      end
    end
    actions.each do |action|
      define_method(action.to_s + '_auth') do
        self.send(action)
        render :action=>action unless performed?
      end
    end
  end
  before_filter before_method, :only=>actions
  actions << options if options
  caches_action  *actions
  before_method
end

Cache is used and created only if controller method authenticated? returns true. Line

self.action_name += '_auth'

Method caches_action_unless_auth could receive options passed to caches_action. So it can be used along with cache_fu and conditional_caching plugins.

-- ArtemVoroztsov - 22 Mar 2008