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Methods
A
Instance Public methods
atom_feed(options = {}, &block)

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:
  Rails.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 actionview/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