Module: ActionController::ConditionalGet

Extended by:
ActiveSupport::Concern
Includes:
Head, RackDelegation
Defined in:
lib/action_controller/metal/conditional_get.rb

Instance Method Summary collapse

Methods included from Head

#head

Methods included from RackDelegation

#dispatch, #reset_session, #response_body=

Instance Method Details

#expires_in(seconds, options = {}) ⇒ Object

Sets a HTTP 1.1 Cache-Control header. Defaults to issuing a “private” instruction, so that intermediate caches shouldn’t cache the response.

Examples:

expires_in 20.minutes
expires_in 3.hours, :public => true
expires in 3.hours, 'max-stale' => 5.hours, :public => true

This method will overwrite an existing Cache-Control header. See www.w3.org/Protocols/rfc2616/rfc2616-sec14.html for more possibilities.



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# File 'lib/action_controller/metal/conditional_get.rb', line 73

def expires_in(seconds, options = {}) #:doc:
  response.cache_control.merge!(:max_age => seconds, :public => options.delete(:public))
  options.delete(:private)

  response.cache_control[:extras] = options.map {|k,v| "#{k}=#{v}"}
end

#expires_now ⇒ Object

Sets a HTTP 1.1 Cache-Control header of “no-cache” so no caching should occur by the browser or intermediate caches (like caching proxy servers).



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# File 'lib/action_controller/metal/conditional_get.rb', line 82

def expires_now #:doc:
  response.cache_control.replace(:no_cache => true)
end

#fresh_when(options) ⇒ Object

Sets the etag, last_modified, or both on the response and renders a “304 Not Modified” response if the request is already fresh.

Parameters:

  • :etag

  • :last_modified

  • :public By default the Cache-Control header is private, set this to true if you want your application to be cachable by other devices (proxy caches).

Example:

def show
  @article = Article.find(params[:id])
  fresh_when(:etag => @article, :last_modified => @article.created_at.utc, :public => true)
end

This will render the show template if the request isn’t sending a matching etag or If-Modified-Since header and just a “304 Not Modified” response if there’s a match.



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# File 'lib/action_controller/metal/conditional_get.rb', line 26

def fresh_when(options)
  options.assert_valid_keys(:etag, :last_modified, :public)

  response.etag          = options[:etag]          if options[:etag]
  response.last_modified = options[:last_modified] if options[:last_modified]
  response.cache_control[:public] = true if options[:public]

  head :not_modified if request.fresh?(response)
end

#stale?(options) ⇒ Boolean

Sets the etag and/or last_modified on the response and checks it against the client request. If the request doesn’t match the options provided, the request is considered stale and should be generated from scratch. Otherwise, it’s fresh and we don’t need to generate anything and a reply of “304 Not Modified” is sent.

Parameters:

  • :etag

  • :last_modified

  • :public By default the Cache-Control header is private, set this to true if you want your application to be cachable by other devices (proxy caches).

Example:

def show
  @article = Article.find(params[:id])

  if stale?(:etag => @article, :last_modified => @article.created_at.utc)
    @statistics = @article.really_expensive_call
    respond_to do |format|
      # all the supported formats
    end
  end
end

Returns:

  • (Boolean) 


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# File 'lib/action_controller/metal/conditional_get.rb', line 58

def stale?(options)
  fresh_when(options)
  !request.fresh?(response)
end