I’m in the middle of developing a Radiant extension for Terralien. Radius is the tagging language for Radiant, and today I figured out how to use a route from inside a custom tag class.

A typical Radius tag class might look like this:

module AwesomeTags
  include Radiant::Taggable
 
  tag "session:logout" do |tag|
    "<a href='/session/logout'>Logout</a>"
  end
end

You can see that the hard-coded URL isn’t exactly DRY. I’ve already defined a route for it. Why should I have to hard code it here? The solution:

module AwesomeTags
  include Radiant::Taggable
  include ActionController::UrlWriter  
  default_url_options[:host] = REGISTRY[:host]
 
  tag "session:logout" do |tag|
    "<a href='#{logout_url}'>Logout</a>"
  end
end

Note that UrlWriter needs to know the host name to base its URLs off of. The host name gets set using the registry pattern. It will be different depending on whether the app is running in development or production mode.

The same method can be used to reference routes from inside ActiveRecord models.