/
conditional_get.rb
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/
conditional_get.rb
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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
# <tt>304 Not Modified</tt> response if the request is already fresh.
#
# === Parameters:
#
# * <tt>:etag</tt>.
# * <tt>:last_modified</tt>.
# * <tt>:public</tt> 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).
# * <tt>:template</tt> 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 <tt>template: false</tt>
# 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 <tt>304 Not Modified</tt> 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 <tt>304 Not Modified</tt> is sent.
#
# === Parameters:
#
# * <tt>:etag</tt>.
# * <tt>:last_modified</tt>.
# * <tt>:public</tt> 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).
# * <tt>:template</tt> 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 <tt>template: false</tt>
# 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 <tt>no-cache</tt> 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