RSS-aware ATOM feed helper
## | |
# RSS-aware patched helper. See http://www.zephyros-systems.co.uk/blog/?p=179 | |
# | |
require 'set' | |
module ActionView | |
# = Action View Atom Feed Helpers | |
module Helpers #:nodoc: | |
module AtomFeedHelper | |
# Adds easy defaults to writing Atom feeds with the Builder template engine (this does not work on ERb or any other | |
# template languages). | |
# | |
# Full usage example: | |
# | |
# config/routes.rb: | |
# Basecamp::Application.routes.draw do | |
# resources :posts | |
# root :to => "posts#index" | |
# end | |
# | |
# app/controllers/posts_controller.rb: | |
# class PostsController < ApplicationController::Base | |
# # GET /posts.html | |
# # GET /posts.atom | |
# def index | |
# @posts = Post.find(:all) | |
# | |
# respond_to do |format| | |
# format.html | |
# format.atom | |
# end | |
# end | |
# end | |
# | |
# app/views/posts/index.atom.builder: | |
# atom_feed do |feed| | |
# feed.title("My great blog!") | |
# feed.updated(@posts.first.created_at) | |
# | |
# for post in @posts | |
# feed.entry(post) do |entry| | |
# entry.title(post.title) | |
# entry.content(post.body, :type => 'html') | |
# | |
# entry.author do |author| | |
# author.name("DHH") | |
# end | |
# end | |
# end | |
# end | |
# | |
# The options for atom_feed are: | |
# | |
# * <tt>:language</tt>: Defaults to "en-US". | |
# * <tt>:root_url</tt>: The HTML alternative that this feed is doubling for. Defaults to / on the current host. | |
# * <tt>:url</tt>: The URL for this feed. Defaults to the current URL. | |
# * <tt>:id</tt>: The id for this feed. Defaults to "tag:#{request.host},#{options[:schema_date]}:#{request.request_uri.split(".")[0]}" | |
# * <tt>:schema_date</tt>: The date at which the tag scheme for the feed was first used. A good default is the year you | |
# created the feed. See http://feedvalidator.org/docs/error/InvalidTAG.html for more information. If not specified, | |
# 2005 is used (as an "I don't care" value). | |
# * <tt>:instruct</tt>: Hash of XML processing instructions in the form {target => {attribute => value, }} or {target => [{attribute => value, }, ]} | |
# | |
# Other namespaces can be added to the root element: | |
# | |
# app/views/posts/index.atom.builder: | |
# atom_feed({'xmlns:app' => 'http://www.w3.org/2007/app', | |
# 'xmlns:openSearch' => 'http://a9.com/-/spec/opensearch/1.1/'}) do |feed| | |
# feed.title("My great blog!") | |
# feed.updated((@posts.first.created_at)) | |
# feed.tag!(openSearch:totalResults, 10) | |
# | |
# for post in @posts | |
# feed.entry(post) do |entry| | |
# entry.title(post.title) | |
# entry.content(post.body, :type => 'html') | |
# entry.tag!('app:edited', Time.now) | |
# | |
# entry.author do |author| | |
# author.name("DHH") | |
# end | |
# end | |
# end | |
# end | |
# | |
# The Atom spec defines five elements (content rights title subtitle | |
# summary) which may directly contain xhtml content if :type => 'xhtml' | |
# is specified as an attribute. If so, this helper will take care of | |
# the enclosing div and xhtml namespace declaration. Example usage: | |
# | |
# entry.summary :type => 'xhtml' do |xhtml| | |
# xhtml.p pluralize(order.line_items.count, "line item") | |
# xhtml.p "Shipped to #{order.address}" | |
# xhtml.p "Paid by #{order.pay_type}" | |
# end | |
# | |
# | |
# atom_feed yields an AtomFeedBuilder instance. Nested elements yield | |
# an AtomBuilder instance. | |
def atom_feed(options = {}, &block) | |
if options[:schema_date] | |
options[:schema_date] = options[:schema_date].strftime("%Y-%m-%d") if options[:schema_date].respond_to?(:strftime) | |
else | |
options[:schema_date] = "2005" # The Atom spec copyright date | |
end | |
xml = options.delete(:xml) || eval("xml", block.binding) | |
xml = rssify(xml) if (rssify = options.delete(:rssify)) | |
xml.instruct! | |
if options[:instruct] | |
options[:instruct].each do |target, attrs| | |
if attrs.respond_to?(:keys) | |
xml.instruct!(target, attrs) | |
elsif attrs.respond_to?(:each) | |
attrs.each { |attr_group| xml.instruct!(target, attr_group) } | |
end | |
end | |
end | |
feed_opts = { | |
"xml:lang" => options[:language] || "en-US", | |
"xmlns#{':a' if rssify}" => 'http://www.w3.org/2005/Atom' | |
} | |
feed_opts.merge!(options).reject! { |k, v| !k.to_s.match(/^xml/) } | |
xml.feed(feed_opts) do | |
xml.id(options[:id] || "tag:#{request.host},#{options[:schema_date]}:#{request.fullpath.split(".")[0]}") | |
xml.link(:rel => 'alternate', :type => 'text/html', :href => options[:root_url] || (request.protocol + request.host_with_port)) | |
xml.link(:rel => 'self', :type => 'application/atom+xml', :href => options[:url] || request.url) | |
yield AtomFeedBuilder.new(xml, self, options) | |
end | |
end | |
## | |
# ATOM elements with their analogues in RSS. Expressed in the form of a hash, | |
# the LHS is the atom name, RHS is *either* a string with the RSS name, *or* | |
# a hash of the RSS name to a custom tagger lambda which will call the xml builder itself | |
# | |
# Anything that is RSS should appear here, even if it has the same element name in ATOM. | |
# Things that don't will fall back to the ATOM namespace. | |
ATOM_RSS_METHOD_MAP = { | |
'id' => 'guid', | |
'title' => 'title', | |
'subtitle' => 'description', | |
'feed' => | |
{ | |
'channel' => lambda do |xml, *options, &block| | |
xml.tag!("rss", :version => '2.0') do | |
xml.tag! "channel", *options, &block | |
end | |
end | |
}, | |
'entry' => 'item', | |
'link' => | |
{ | |
'link' => lambda do |xml, *options, &block| | |
tag_with = 'link' | |
rel = options.last[:rel] | |
if rel == 'alternate' && options.last[:type] == 'text/html' | |
options.last.delete(:rel) | |
options.last.delete(:type) | |
options.unshift(options.last.delete(:href)) | |
else | |
tag_with = 'a:link' | |
end | |
xml.tag! tag_with, *options, &block | |
end | |
}, | |
'content' => | |
{ | |
'description' => lambda do |xml, *options, &block| | |
# 'description' element has no type="html"" | |
options.last.delete(:type) | |
xml.tag! 'description', *options, &block | |
end | |
}, | |
'published' => | |
{ | |
'pubDate' => lambda do |xml, *options, &block| | |
options[0] = DateTime.parse(options[0]).rfc822 | |
xml.tag! 'pubDate', *options, &block | |
end | |
} | |
} | |
## | |
# Modify this instance of Builder::XmlMarkup to | |
# intercept atom calls and patch them to their RSS equivalents | |
def rssify(xml) | |
ATOM_RSS_METHOD_MAP.each_pair do |atom_name, handler| | |
rss_method_name, custom_tagger = *(handler.is_a?(Hash) ? | |
[handler.keys.first, handler.values.first] : [handler, nil]) | |
xml.class_eval do | |
define_method atom_name do |*options, &block| | |
if custom_tagger | |
custom_tagger.call(xml, *options, &block) | |
else | |
xml.tag!(rss_method_name, *options, &block) | |
end | |
end | |
end | |
end | |
## | |
# Define the fallback to atom for method_missing | |
xml.class_eval do | |
define_method :method_missing_with_fallback_to_atom do |sym, *args, &block| | |
# Violation of DRY (see ATOM_RSS_METHOD_MAP above). TODO: make it not one. | |
@@known ||= [:rss, :title, :description, :guid, :channel, :item, :link, :description, :pubDate] | |
sym_s = sym.to_s | |
sym = "a:#{sym_s}".to_sym unless @@known.include?(sym) || sym_s.include?(':') | |
method_missing_without_fallback_to_atom sym, *args, &block | |
end | |
alias_method_chain :method_missing, :fallback_to_atom | |
end | |
xml | |
end | |
class AtomBuilder | |
(XHTML_TAG_NAMES = %w(content rights title subtitle summary).to_set) unless defined?(XHTML_TAG_NAMES) | |
def initialize(xml) | |
@xml = xml | |
end | |
private | |
# Delegate to xml builder, first wrapping the element in a xhtml | |
# namespaced div element if the method and arguments indicate | |
# that an xhtml_block? is desired. | |
def method_missing(method, *arguments, &block) | |
if xhtml_block?(method, arguments) | |
@xml.__send__(method, *arguments) do | |
@xml.div(:xmlns => 'http://www.w3.org/1999/xhtml') do |xhtml| | |
block.call(xhtml) | |
end | |
end | |
else | |
@xml.__send__(method, *arguments, &block) | |
end | |
end | |
# True if the method name matches one of the five elements defined | |
# in the Atom spec as potentially containing XHTML content and | |
# if :type => 'xhtml' is, in fact, specified. | |
def xhtml_block?(method, arguments) | |
if XHTML_TAG_NAMES.include?(method.to_s) | |
last = arguments.last | |
last.is_a?(Hash) && last[:type].to_s == 'xhtml' | |
end | |
end | |
end | |
class AtomFeedBuilder < AtomBuilder | |
def initialize(xml, view, feed_options = {}) | |
@xml, @view, @feed_options = xml, view, feed_options | |
end | |
# Accepts a Date or Time object and inserts it in the proper format. If nil is passed, current time in UTC is used. | |
def updated(date_or_time = nil) | |
@xml.updated((date_or_time || Time.now.utc).xmlschema) | |
end | |
# Creates an entry tag for a specific record and prefills the id using class and id. | |
# | |
# Options: | |
# | |
# * <tt>:published</tt>: Time first published. Defaults to the created_at attribute on the record if one such exists. | |
# * <tt>:updated</tt>: Time of update. Defaults to the updated_at attribute on the record if one such exists. | |
# * <tt>:url</tt>: The URL for this entry. Defaults to the polymorphic_url for the record. | |
# * <tt>:id</tt>: The ID for this entry. Defaults to "tag:#{@view.request.host},#{@feed_options[:schema_date]}:#{record.class}/#{record.id}" | |
def entry(record, options = {}) | |
@xml.entry do | |
@xml.id(options[:id] || "tag:#{@view.request.host},#{@feed_options[:schema_date]}:#{record.class}/#{record.id}") | |
if options[:published] || (record.respond_to?(:created_at) && record.created_at) | |
@xml.published((options[:published] || record.created_at).xmlschema) | |
end | |
if options[:updated] || (record.respond_to?(:updated_at) && record.updated_at) | |
@xml.updated((options[:updated] || record.updated_at).xmlschema) | |
end | |
@xml.link(:rel => 'alternate', :type => 'text/html', :href => options[:url] || @view.polymorphic_url(record)) | |
yield AtomBuilder.new(@xml) | |
end | |
end | |
end | |
end | |
end | |
end | |
module RssAwareAtomFeedHelper | |
# Keeps ActiveRecord dependencies quiet. TODO: find a way of removing | |
end |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment