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https://github.com/rails/actionpack-action_caching

Action caching for Action Pack (removed from core in Rails 4.0)
https://github.com/rails/actionpack-action_caching

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Action caching for Action Pack (removed from core in Rails 4.0)

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README 

        
actionpack-action_caching

=========================



Action caching for Action Pack (removed from core in Rails 4.0).



Installation

------------



Add this line to your application's Gemfile:



```ruby

gem 'actionpack-action_caching'

```



And then execute:



    $ bundle



Or install it yourself as:



    $ gem install actionpack-action_caching



Usage

-----



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 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.



```ruby

class ListsController < ApplicationController

  before_action :authenticate, except: :public



  caches_page   :public

  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. On the other hand

`index` and `show` require authentication. They can still be cached,

but we need action caching for them.



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

`jamis.example.com/lists/` -- which is a helpful way of assisting

the subdomain-as-account-key pattern.



Different representations of the same resource, e.g.

`http://david.example.com/lists` and

`http://david.example.com/lists.xml`

are treated like separate requests and so are cached separately.

Keep in mind when expiring an action cache that

`action: "lists"` is not the same as

`action: "list", format: :xml`.



You can modify the default action cache path by passing a

`:cache_path` option. This will be passed directly to

`ActionCachePath.new`. This is handy for actions with

multiple possible routes that should be cached differently. If a

proc (or an object that responds to `to_proc`) is given, it is

called with the current controller instance.



And you can also use `:if` (or `:unless`) to control when the action

should be cached, similar to how you use them with `before_action`.



As of Rails 3.0, you can also pass `:expires_in` with a time

interval (in seconds) to schedule expiration of the cached item.



The following example depicts some of the points made above:



```ruby

class ListsController < ApplicationController

  before_action :authenticate, except: :public



  # simple fragment cache

  caches_action :current



  # expire cache after an hour

  caches_action :archived, expires_in: 1.hour



  # cache unless it's a JSON request

  caches_action :index, unless: -> { request.format.json? }



  # custom cache path

  caches_action :show, cache_path: { project: 1 }



  # custom cache path with a proc

  caches_action :history, cache_path: -> { request.domain }



  # custom cache path with a symbol

  caches_action :feed, cache_path: :user_cache_path



  protected

    def user_cache_path

      if params[:user_id]

        user_list_url(params[:user_id], params[:id])

      else

        list_url(params[:id])

      end

    end

end

```



If you pass `layout: false`, it will only cache your action

content. That's useful when your layout has dynamic information.



Note: Both the `:format` param and the `Accept` header are taken

into account when caching the fragment with the `:format` having

precedence. For backwards compatibility when the `Accept` header

indicates a HTML request the fragment is stored without the

extension but if an explicit `"html"` is passed in `:format` then

that _is_ used for storing the fragment.



Contributing

------------



1. Fork it.

2. Create your feature branch (`git checkout -b my-new-feature`).

3. Commit your changes (`git commit -am 'Add some feature'`).

4. Push to the branch (`git push origin my-new-feature`).

5. Create a new Pull Request.



Code Status

-----------



* [![Build Status](https://github.com/rails/actionpack-action_caching/actions/workflows/ci.yml/badge.svg)](https://github.com/rails/actionpack-action_caching/actions/workflows/ci.yml)