generate nofollow links in RDiscount output

Question

My rails app is using RDiscount to generate HTML from user-supplied markdown text, and I noticed that the anchor tags don't have rel="nofollow". This is a big issue for me as my app is open to the public. Is there a way to enable nofollow links, or are there better solutions?

Thanks!

score 3 · Answer 1 · answered Jan 16 '11 at 13:34

3

I think this is possible only with Kramdown, which is a ruby Markdown parser with extended syntax. You would do that then as shown in the link:

[link](test.html){:rel='nofollow'}

answered Jan 16 '11 at 13:34

farnoy

7,356
2
20
30

Actually the content will be supplied by the user, so I need a way to automatically add rel="nofollow" to every link as a measure to discourage SEO spam. I think stackoverflow does it. – widgetycrank Jan 16 '11 at 22:35

score 2 · Answer 2 · answered Jan 17 '11 at 00:28

In the mean time, I am using this hack, by re-parsing the RDiscount output and add a rel="nofollow" to each anchor:

def markdown(input)
  html = RDiscount.new(input).to_html
  doc = Nokogiri::HTML::DocumentFragment.parse(html)
  doc.css("a").each do |link|
    link['rel'] = 'nofollow'
  end
  doc.to_html
end

Though I think this should really be handled by the markdown parser.

score 1 · Answer 3 · answered Oct 18 '11 at 13:14

I needed to do something similar, add target="_new" to all links. Solved it using Kramdown and a custom Kramdown::Converter::Html class.

Define a Kramdown::Converter::Html subclass (kramdown/converter/my_html.rb in some autoload path)

class Kramdown::Converter::MyHtml < Kramdown::Converter::Html
  def convert_a(el, indent)
    el.attr['target'] = '_new'
    super
  end
end

I also have a view helper in app/helpers/application_helper.rb

def markdown(str)
  Kramdown::Converter::MyHtml.convert(Kramdown::Document.new(str).root)[0].html_safe
end

Ideally it should be possible to just use Kramdown::Document.new(str).to_my_html.html_safe but I can't get it to work in rails development mode as Kramdown uses const_defined? to see if a converter is available and that does not trigger the autoloader. Please comment if you know how to fix this.

score 0 · Answer 4 · answered Apr 28 '13 at 16:30

0

There is an open feature request on RDiscount to support modifying links in this fashion.

It is scheduled for one of the upcoming RDiscount 2.1.5.x releases.

answered Apr 28 '13 at 16:30

David Foster

6,931
4
41
42

generate nofollow links in RDiscount output

4 Answers4