This post originated from an RSS feed registered with Ruby Buzz
by Ryan Davis.
Original Post: Overriding url_for for Fun and Profit
Feed Title: Polishing Ruby
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A while back I was thinking about MVC and how URLs are built and came to the conclusion that every model should know what its URL is. I don't think it is the responsibility of the Controller to know this, and certainly not the view.
Since Rails uses a Hash to represent a URL, I thought it would be easy to just add a method to every Model that would return a Hash representation of the URL and override url_for to perform the expansion from a model into its URL Hash.
It turns out that it was easy. After some enhancements by Ryan that adds defaults we came up with the following:
class ApplicationController < ActionController::Base
def url_for(options = {}, *params)
if options.include? :model then
model = options.delete(:model)
defaults = {
:action => 'show',
:id => model.id,
:controller => model.class.name.downcase,
}
defaults = defaults.merge model.url_params if model.respond_to? :url_params
options.delete :only_path if defaults.include? :only_path
options = defaults.merge options
end
return super(options, *params)
end
end
Sometimes the defaults aren't good enough though. To override them you add a url_params method to your model. In Trackmap I store enough information about a flickr photo to generate its flickr URL in the database and my url_for modification (with a bit of cheating) makes this very clean:
class Photo < ActiveRecord::Base
#...
def url_params
return { :host => 'flickr.com', :controller => 'photos',
:action => flickr_nsid, :id => flickr_photo_id,
:only_path => false }
end
end