From 0aa78826e4857dbaaaf8a0779848d11ab6e0ad5d Mon Sep 17 00:00:00 2001 From: Xavier Noria Date: Wed, 8 Dec 2010 21:20:53 +0100 Subject: makes a pass to the action caching rdoc --- .../lib/action_controller/caching/actions.rb | 73 ++++++++++++---------- 1 file changed, 41 insertions(+), 32 deletions(-) diff --git a/actionpack/lib/action_controller/caching/actions.rb b/actionpack/lib/action_controller/caching/actions.rb index cb79e51dbf..a4bac3caed 100644 --- a/actionpack/lib/action_controller/caching/actions.rb +++ b/actionpack/lib/action_controller/caching/actions.rb @@ -4,25 +4,26 @@ module ActionController #:nodoc: module Caching # Action caching is similar to page caching by the fact that the entire # output of the response is cached, but unlike page caching, every - # request still goes through the Action Pack. The key benefit - # of this is that filters are run before the cache is served, which - # allows for authentication and other restrictions on whether someone - # is allowed to see the cache. Example: + # request still goes through Action Pack. The key benefit of this is + # that filters run before the cache is served, which allows for + # authentication and other restrictions on whether someone is allowed + # to execute such action. Example: # # class ListsController < ApplicationController # before_filter :authenticate, :except => :public + # # caches_page :public - # caches_action :index, :show, :feed + # caches_action :index, :show # end # - # In this example, the public action doesn't require authentication, - # so it's possible to use the faster page caching method. But both - # the show and feed action are to be shielded behind the authenticate - # filter, so we need to implement those as action caches. + # In this example, the +public+ action doesn't require authentication + # so it's possible to use the faster page caching. On the other hand + # +index+ and +show+ require authentication. They can still be cached, + # but we need action caching for them. # - # Action caching internally uses the fragment caching and an around - # filter to do the job. The fragment cache is named according to both - # the current host and the path. So a page that is accessed at + # Action caching uses fragment caching internally and an around + # filter to do the job. The fragment cache is named according to + # the host and path of the request. A page that is accessed at # http://david.example.com/lists/show/1 will result in a fragment named # david.example.com/lists/show/1. This allows the cacher to # differentiate between david.example.com/lists/ and @@ -38,19 +39,23 @@ module ActionController #:nodoc: # :action => 'list', :format => :xml. # # You can set modify the default action cache path by passing a - # :cache_path option. This will be passed directly to - # ActionCachePath.path_for. This is handy for actions with multiple - # possible routes that should be cached differently. If a block is - # given, it is called with the current controller instance. + # :cache_path option. This will be passed directly to + # ActionCachePath.path_for. This is handy for actions with + # multiple possible routes that should be cached differently. If a + # block is given, it is called with the current controller instance. + # + # And you can also use :if (or :unless) to pass a + # proc that specifies when the action should be cached. # - # And you can also use :if (or :unless) to pass a Proc that - # specifies when the action should be cached. + # Finally, if you are using memcached, you can also pass :expires_in. # - # Finally, if you are using memcached, you can also pass :expires_in. + # The following example depicts some of the points made above: # # class ListsController < ApplicationController # before_filter :authenticate, :except => :public - # caches_page :public + # + # caches_page :public + # # caches_action :index, :if => proc do |c| # !c.request.format.json? # cache if is not a JSON request # end @@ -58,24 +63,28 @@ module ActionController #:nodoc: # caches_action :show, :cache_path => { :project => 1 }, # :expires_in => 1.hour # - # caches_action :feed, :cache_path => proc do |controller| - # if controller.params[:user_id] - # controller.send(:user_list_url, - # controller.params[:user_id], controller.params[:id]) + # caches_action :feed, :cache_path => proc do |c| + # if c.params[:user_id] + # c.send(:user_list_url, + # c.params[:user_id], c.params[:id]) # else - # controller.send(:list_url, controller.params[:id]) + # c.send(:list_url, c.params[:id]) # end # end # end # - # If you pass :layout => false, it will only cache your action - # content. It is useful when your layout has dynamic information. + # If you pass :layout => false, it will only cache your action + # content. That's useful when your layout has dynamic information. + # + # Warning: If the format of the request is determined by the Accept HTTP + # header the Content-Type of the cached response could be wrong because + # no information about the MIME type is stored in the cache key. So, if + # you first ask for MIME type M in the Accept header, a cache entry is + # created, and then perform a second resquest to the same resource asking + # for a different MIME type, you'd get the content cached for M. # - # Note: If action caching is being performed for different MIME types - # and those MIME types are being determined by HTTP_ACCEPT header atttribute - # and noth using params[:format] then both the cached data and the content-type - # of the response could be wrong. The safest way to use action caching is to - # pass non-html attribute as params[:format] . + # The :format parameter is taken into account though. The safest + # way to cache by MIME type is to pass the format in the route. module Actions extend ActiveSupport::Concern -- cgit v1.2.3