Last Modified
2014-11-13 16:28:14 -0700
Requires
  • rss/1.0
  • rss/2.0
  • rss/atom
  • rss/content
  • rss/dublincore
  • rss/image
  • rss/itunes
  • rss/slash
  • rss/syndication
  • rss/taxonomy
  • rss/trackback
  • rss/maker

Description

RSS reading and writing

Really Simple Syndication (RSS) is a family of formats that describe ‘feeds,’ specially constructed XML documents that allow an interested person to subscribe and receive updates from a particular web service. This portion of the standard library provides tooling to read and create these feeds.

The standard library supports RSS 0.91, 1.0, 2.0, and Atom, a related format. Here are some links to the standards documents for these formats:

Consuming RSS

If you’d like to read someone’s RSS feed with your Ruby code, you’ve come to the right place. It’s really easy to do this, but we’ll need the help of open-uri:

require 'rss'
require 'open-uri'

url = 'http://www.ruby-lang.org/en/feeds/news.rss'
open(url) do |rss|
  feed = RSS::Parser.parse(rss)
  puts "Title: #{feed.channel.title}"
  feed.items.each do |item|
    puts "Item: #{item.title}"
  end
end

As you can see, the workhorse is RSS::Parser#parse, which takes the source of the feed and a parameter that performs validation on the feed. We get back an object that has all of the data from our feed, accessible through methods. This example shows getting the title out of the channel element, and looping through the list of items.

Producing RSS

Producing our own RSS feeds is easy as well. Let’s make a very basic feed:

require "rss"

rss = RSS::Maker.make("atom") do |maker|
  maker.channel.author = "matz"
  maker.channel.updated = Time.now.to_s
  maker.channel.about = "http://www.ruby-lang.org/en/feeds/news.rss"
  maker.channel.title = "Example Feed"

  maker.items.new_item do |item|
    item.link = "http://www.ruby-lang.org/en/news/2010/12/25/ruby-1-9-2-p136-is-released/"
    item.title = "Ruby 1.9.2-p136 is released"
    item.updated = Time.now.to_s
  end
end

puts rss

As you can see, this is a very Builder-like DSL. This code will spit out an Atom feed with one item. If we needed a second item, we’d make another block with maker.items.new_item and build a second one.

Copyright © 2003-2007 Kouhei Sutou <kou@cozmixng.org>

You can redistribute it and/or modify it under the same terms as Ruby.

There is an additional tutorial by the author of RSS at: www.cozmixng.org/~rwiki/?cmd=view;name=RSS+Parser%3A%3ATutorial.en

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.

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