Question

v. Rails 2.3.8

What I’m looking to achieve is to dynamically modify outbound links in Rails so that the changes are cached using fragment caching. How would you go about doing this?

Note: This time I am intentionally not including my own ideas and source code here, as I’d like to hear suggestions without bias.

Thanks.

Answer 1

Here is the solution:

In ActionController::Caching::Fragments.fragment_for, change these lines:

pos = buffer.length
block.call
write_fragment(name, buffer[pos..-1], options)

to this:

pos = buffer.length
fragment = Nokogiri::HTML::fragment(block.call)
fragment.css('a').each do |a|
  unless a['href'].nil?
    a.set_attribute('rel', 'nofollow') unless (a['href'].starts_with?('/') || a['href'].starts_with?("http://#{ENV['BASE_URL']}"))
  end
end
buffer[pos..-1] = fragment.to_html
write_fragment(name, buffer[pos..-1], options)

Please note that:

1. I use ENV[‘BASE_URL’] to store the base URL of the site (loaded from
   database during initialization).
2. You must have the Nokogiri gem installed.
3. This solution works for Rails 2.3.8 – I have not tested in version 3.