require 'active_support/core_ext/hash/keys' module ActionController module ConditionalGet extend ActiveSupport::Concern include RackDelegation include Head included do class_attribute :etaggers self.etaggers = [] end module ClassMethods # Allows you to consider additional controller-wide information when generating an ETag. # For example, if you serve pages tailored depending on who's logged in at the moment, you # may want to add the current user id to be part of the ETag to prevent authorized displaying # of cached pages. # # class InvoicesController < ApplicationController # etag { current_user.try :id } # # def show # # Etag will differ even for the same invoice when it's viewed by a different current_user # @invoice = Invoice.find(params[:id]) # fresh_when(@invoice) # end # end def etag(&etagger) self.etaggers += [etagger] end end # 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). # * :template By default, the template digest for the current # controller/action is included in ETags. If the action renders a # different template, you can include its digest instead. If the action # doesn't render a template at all, you can pass template: false # to skip any attempt to check for a template digest. # # === 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. # # You can also just pass a record where +last_modified+ will be set by calling # +updated_at+ and the +etag+ by passing the object itself. # # def show # @article = Article.find(params[:id]) # fresh_when(@article) # end # # When passing a record, you can still set whether the public header: # # def show # @article = Article.find(params[:id]) # fresh_when(@article, public: true) # end # # When rendering a different template than the default controller/action # style, you can indicate which digest to include in the ETag: # # before_action { fresh_when @article, template: 'widgets/show' } # def fresh_when(record_or_options, additional_options = {}) if record_or_options.is_a? Hash options = record_or_options options.assert_valid_keys(:etag, :last_modified, :public, :template) else record = record_or_options options = { etag: record, last_modified: record.try(:updated_at) }.merge!(additional_options) end response.etag = combine_etags(options) if options[:etag] || options[:template] 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 # 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). # * :template By default, the template digest for the current # controller/action is included in ETags. If the action renders a # different template, you can include its digest instead. If the action # doesn't render a template at all, you can pass template: false # to skip any attempt to check for a template digest. # # === 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 # # You can also just pass a record where +last_modified+ will be set by calling # +updated_at+ and the +etag+ by passing the object itself. # # def show # @article = Article.find(params[:id]) # # if stale?(@article) # @statistics = @article.really_expensive_call # respond_to do |format| # # all the supported formats # end # end # end # # When passing a record, you can still set whether the public header: # # def show # @article = Article.find(params[:id]) # # if stale?(@article, public: true) # @statistics = @article.really_expensive_call # respond_to do |format| # # all the supported formats # end # end # end # # When rendering a different template than the default controller/action # style, you can indicate which digest to include in the ETag: # # def show # super if stale? @article, template: 'widgets/show' # end # def stale?(record_or_options, additional_options = {}) fresh_when(record_or_options, additional_options) !request.fresh?(response) end # Sets a HTTP 1.1 Cache-Control header. Defaults to issuing a +private+ # instruction, so that intermediate caches must not cache the response. # # expires_in 20.minutes # expires_in 3.hours, public: true # expires_in 3.hours, public: true, must_revalidate: true # # This method will overwrite an existing Cache-Control header. # See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html for more possibilities. # # The method will also ensure a HTTP Date header for client compatibility. def expires_in(seconds, options = {}) response.cache_control.merge!( :max_age => seconds, :public => options.delete(:public), :must_revalidate => options.delete(:must_revalidate) ) options.delete(:private) response.cache_control[:extras] = options.map {|k,v| "#{k}=#{v}"} response.date = Time.now unless response.date? end # 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). def expires_now response.cache_control.replace(:no_cache => true) end private def combine_etags(options) etags = etaggers.map { |etagger| instance_exec(options, &etagger) }.compact etags.unshift options[:etag] end end end