module ActionController
module ConditionalGet
extend ActiveSupport::Concern
include RackDelegation
include Head
# 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).
#
# 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. Example:
#
# 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
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)
else
record = record_or_options
options = { :etag => record, :last_modified => record.try(:updated_at) }.merge(additional_options)
end
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
# 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).
#
# 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. Example:
#
# 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
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 <tt>private</tt> 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, :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 = {}) #:doc:
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 #:doc:
response.cache_control.replace(:no_cache => true)
end
end
end
