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ActionController::ConditionalGet

Public Instance Methods

expires_in(seconds, options = {}) click to toggle source

Sets a HTTP 1.1 Cache-Control header. Defaults to issuing a private instruction, so that intermediate caches must not 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.

# 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() click to toggle source

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).

# 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) click to toggle source

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, :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.

# 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) click to toggle source

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)
    @statistics = @article.really_expensive_call
    respond_to do |format|
      # all the supported formats
    end
  end
end
# File lib/action_controller/metal/conditional_get.rb, line 58
def stale?(options)
  fresh_when(options)
  !request.fresh?(response)
end

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