# module ActionView::Helpers::AtomFeedHelper

### Public Instance Methods

atom_feed(options = {}) { |atom_feed_builder| ... } click to toggle source

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.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[0].created_at) if @posts.length > 0

        @posts.each do |post|
          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:

- `:language`: Defaults to "en-US".

- `:root_url`: The HTML alternative that this feed is doubling for. Defaults to / on the current host.

- `:url`: The URL for this feed. Defaults to the current URL.

- `:id`: The id for this feed. Defaults to "tag:#{request.host},#{options}:#{request.fullpath.split(".")}"

- `:schema_date`: The date at which the tag scheme for the feed was first used. A good default is the year you created the feed. See feedvalidator.org/docs/error/InvalidTAG.html for more information. If not specified, 2005 is used (as an "I don't care" value).

- `:instruct`: 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)

        @posts.each do |post|
          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.

    # File lib/action_view/helpers/atom_feed_helper.rb, line 96
    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.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" => '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