Add api key to every request in ActiveResource

Question

I have 2 RESTful Rails apps I'm trying to make talk to each other. Both are written in Rails 3 (beta3 at the moment). The requests to the service will require the use an api key which is just a param that needs to be on every request. I can't seem to find any information on how to do this.

You define the url the resource connects to via the site= method. There should be an equivalent query_params= method or similar.

There is one good blog post I found related to this and it's from October 2008, so not exactly useful for Rails 3.

Update: I had a thought. Would a small Rack middleware or Metal be the answer to this? It could just pass through the request, tacking it's api_key on.

Answer 1

Based on Joel Azemar's answer, but I had to make some changes.. First of all, in the active resource gem I used (2.3.8), there is no 'new_element_path', so aliasing that obviously failed.. Second, I updated the way the token is added to the query, because as was, it would break as soon as you add more params yourself. E.g. request for http://example.com/api/v1/clients.xml?vat=0123456789?token=xEIx6fBsxy6sKLJMPVM4 (notice ?token= i.o. &token=)

Here's my updated snippet auth_with_api.rb;

module ActiveResource #:nodoc:
  module Extend
    module AuthWithApi
      module ClassMethods
        def element_path_with_auth(id, prefix_options = {}, query_options = nil)
          query_options.merge!({:token => self.api_key})
          element_path_without_auth(id, prefix_options, query_options)
        end
        def collection_path_with_auth(prefix_options = {}, query_options = nil)
          query_options.merge!({:token => self.api_key})
          collection_path_without_auth(prefix_options, query_options)
        end
      end

      def self.included(base)
        base.class_eval do
          extend ClassMethods
          class << self
            alias_method_chain :element_path, :auth
            # alias_method_chain :new_element_path, :auth
            alias_method_chain :collection_path, :auth
            attr_accessor :api_key
          end
        end
      end  
    end
  end
end