Early experiences with Active Resource

Last updated 23:04 BST Fri 30 June.

At the recent RailsConf David Heinemeier Hansson announced his ideas for an active resource library in rails. His slides are available here.

Unfortunately the early version he checked into the rails edge repository doesn’t quite match his slides.

Below are my (in progress) notes on getting it to work.

Pre-requisites

You need edge rails: rake rails:freeze:edge

You need some rest-ful type routes. I’ve used: script/plugin install simply_restful

You need a controller that has the same name as your model (e.g. PeopleController) with index, new, create, show, edit, update and delete methods. Each of these needs to respond sensibly to xml requests, e.g.:

def show
    @patch = Patch.find(params[:id])
    respond_to do |format|
      format.html
      format.xml { render :xml => @patch.to_xml }
    end
  end

Initialization

The example that DHH gave:

Person = ActiveResource::Struct.new do |person|
  person.uri = "http://api.myremote.com/people" 
  person.credentials :name => "me", :password => "password" 
end

What works in the code:

Person = ActiveResource::Struct.create
Person.site = "http://api.myremote.com/people"

Get

You can then get an object:

p = Person.find 1

There is an error if you try and find(:all) and no objects exists.

Put / Update

Saving doesn’t work, because ActiveResource doesn’t set the content-type. Adding this at the start of the request method in ActiveResource::Connection seems to help:

arguments << { 'content-type' => 'application/xml' }

Post / Create

Creating a record doesn’t work, as Person.save currently goes straight to the put method.

I made this changes to get a create function:

ActiveResource::Base

def save
    id ? update : create
end

def create
  attributes["id"] = connection.post(self.class.collection_path, to_xml)
end

ActiveResource::Connection

def post(path, body)
  response = request(:post, path, body)
  return response['Location'][/\/([^\/]*?)$/,1] # The id
end