module ActionController
module ConditionalGet
# Sets the etag, last_modified, or both on the response and renders a
# "304 Not Modified" 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.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.
#
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]
if options[:public]
cache_control = response.headers["Cache-Control"].split(",").map {|k| k.strip }
cache_control.delete("private")
cache_control.delete("no-cache")
cache_control << "public"
response.headers["Cache-Control"] = cache_control.join(', ')
end
if request.fresh?(response)
head :not_modified
end
end
# Return a response that has no content (merely headers). The options
# argument is interpreted to be a hash of header names and values.
# This allows you to easily return a response that consists only of
# significant headers:
#
# head :created, :location => person_path(@person)
#
# It can also be used to return exceptional conditions:
#
# return head(:method_not_allowed) unless request.post?
# return head(:bad_request) unless valid_request?
# render
def head(*args)
if args.length > 2
raise ArgumentError, "too many arguments to head"
elsif args.empty?
raise ArgumentError, "too few arguments to head"
end
options = args.extract_options!
status = args.shift || options.delete(:status) || :ok
options.each do |key, value|
headers[key.to_s.dasherize.split(/-/).map { |v| v.capitalize }.join("-")] = value.to_s
end
render :nothing => true, :status => status
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:
# * <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.utc)
# @statistics = @article.really_expensive_call
# respond_to do |format|
# # all the supported formats
# end
# end
# end
def stale?(options)
fresh_when(options)
!request.fresh?(response)
end
# 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 http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html for more possibilities.
def expires_in(seconds, options = {}) #:doc:
cache_control = response.headers["Cache-Control"].split(",").map {|k| k.strip }
cache_control << "max-age=#{seconds}"
cache_control.delete("no-cache")
if options[:public]
cache_control.delete("private")
cache_control << "public"
else
cache_control << "private"
end
# This allows for additional headers to be passed through like 'max-stale' => 5.hours
cache_control += options.symbolize_keys.reject{|k,v| k == :public || k == :private }.map{ |k,v| v == true ? k.to_s : "#{k.to_s}=#{v.to_s}"}
response.headers["Cache-Control"] = cache_control.join(', ')
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 #:doc:
response.headers["Cache-Control"] = "no-cache"
end
end
end
