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Module: ActionController::Caching::Fragments

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
::ActionController::Base, ::ActionController::Caching, ::ActionView::TestCase::TestController, Rails::ApplicationController, Rails::InfoController, Rails::MailersController, Rails::WelcomeController
Defined in: actionpack/lib/action_controller/caching/fragments.rb

Overview

Fragment caching is used for caching various blocks within views without caching the entire action as a whole. This is useful when certain elements of an action change frequently or depend on complicated state while other parts rarely change or can be shared amongst multiple parties. The caching is done using the #cache helper available in the Action View. See ::ActionView::Helpers::CacheHelper for more information.

While it's strongly recommended that you use key-based cache expiration (see links in CacheHelper for more information), it is also possible to manually expire caches. For example:

expire_fragment('name_of_cache')

Instance Method Summary

Instance Method Details

#expire_fragment(key, options = nil)

Removes fragments from the cache.

key can take one of three forms:

  • ::String - This would normally take the form of a path, like pages/45/notes.

  • ::Hash - Treated as an implicit call to url_for, like { controller: 'pages', action: 'notes', id: 45}

  • ::Regexp - Will remove any fragment that matches, so %r{pages/\d*/notes} might remove all notes. Make sure you don't use anchors in the regex (^ or $) because the actual filename matched looks like ./cache/filename/path.cache. Note: Regexp expiration is only supported on caches that can iterate over all keys (unlike memcached).

options is passed through to the cache store's delete method (or delete_matched, for ::Regexp keys).

[ GitHub ] 

  


# File 'actionpack/lib/action_controller/caching/fragments.rb', line 79



def expire_fragment(key, options = nil)
  return unless cache_configured?
  key = fragment_cache_key(key) unless key.is_a?(Regexp)

  instrument_fragment_cache :expire_fragment, key do
    if key.is_a?(Regexp)
      cache_store.delete_matched(key, options)
    else
      cache_store.delete(key, options)
    end
  end
end


  








  

    #fragment_cache_key(key)  
  



  

    

Given a key (as described in #expire_fragment), returns a key suitable for use in reading, writing, or expiring a cached fragment. All keys are prefixed with views/ and uses ActiveSupport::Cache.expand_cache_key for the expansion.


  



  [ GitHub ]


  

  


# File 'actionpack/lib/action_controller/caching/fragments.rb', line 21



def fragment_cache_key(key)
  ActiveSupport::Cache.expand_cache_key(key.is_a?(Hash) ? url_for(key).split("://").last : key, :views)
end


  








  

    #fragment_exist?(key, options = nil)  ⇒ Boolean 
  



  

    

Check if a cached fragment from the location signified by key exists (see #expire_fragment for acceptable formats).


  





  


  [ GitHub ]


  

  


# File 'actionpack/lib/action_controller/caching/fragments.rb', line 52



def fragment_exist?(key, options = nil)
  return unless cache_configured?
  key = fragment_cache_key(key)

  instrument_fragment_cache :exist_fragment?, key do
    cache_store.exist?(key, options)
  end
end


  








  

    #read_fragment(key, options = nil)  
  



  

    

Reads a cached fragment from the location signified by key (see #expire_fragment for acceptable formats).


  



  [ GitHub ]


  

  


# File 'actionpack/lib/action_controller/caching/fragments.rb', line 40



def read_fragment(key, options = nil)
  return unless cache_configured?

  key = fragment_cache_key(key)
  instrument_fragment_cache :read_fragment, key do
    result = cache_store.read(key, options)
    result.respond_to?(:html_safe) ? result.html_safe : result
  end
end


  








  

    #write_fragment(key, content, options = nil)  
  



  

    

Writes content to the location signified by key (see #expire_fragment for acceptable formats).


  



  [ GitHub ]


  

  


# File 'actionpack/lib/action_controller/caching/fragments.rb', line 27



def write_fragment(key, content, options = nil)
  return content unless cache_configured?

  key = fragment_cache_key(key)
  instrument_fragment_cache :write_fragment, key do
    content = content.to_str
    cache_store.write(key, content, options)
  end
  content
end