Monday, August 25, 2008

rubyjs_on_rails hackfest at erubycon

I had a really fun time hacking on rubyjs at eRubycon. It's amazing how much more fun and productive it is to hack with someone else than by yourself. Thanks to Corey Haines for staying up late at the hotel being my hacking buddy. As a result, we now have what will be the beginning of an ActiveResource client for rubyjs_on_rails. I generated a simple scaffold resource example called Customer with a few fields. I then created a Customer class in the view and started getting it to speak restfully with rails. Here's the result:

require 'dom_element'
require 'json'
require 'rwt/HTTPRequest'

class Customer

attr_accessor :attributes

def initialize(attrs)
@attributes = attrs

def method_missing(method, *args)
if method =~ /(.*)=$/
attributes[$1] = args[0]
elsif attributes[method]

def self.main
@name = DOMElement.find("name")
@address = DOMElement.find("address")
find_button = DOMElement.find("choose_customer_button")
save_button = DOMElement.find("save_button")
customer_id_text = DOMElement.find("customer_id")

find_button.observe("click") do |event|
Customer.find(customer_id_text["value"]) do |customer|
@name["value"] =
@address["value"] = customer.address
@customer = customer

save_button.observe("click") do |event| = @name["value"]
@customer.address = @address["value"]

rescue StandardError => ex
puts ex

def self.find(id)
HTTPRequest.asyncGet "/customers/#{id}.json" do |json|
hash = JSON.load(json)

def save
request_json = {:customer => attributes}.to_json
HTTPRequest.asyncImpl "/customers/#{id}.json", "PUT", request_json, "application/json" do |json|
self.attributes = JSON.load(json)

def to_json

The first part I did was find. I've had that done for a couple weeks. This was super easy because rubyjs and rails support json so easily. The only odd bit is that it takes a block instead of returning a result. This is because the find call does an ajax request, and the a in ajax stands for.. you guessed it, asynchronous. Passing a block in makes it nice and simple to handle the result easily though.

The part I got working at rubycon was the save. This proved to be much easier than I thought it would be as well due to rails now supporting json updates natively. The controller code doesn't even need to be aware that the parameters are coming in as json, you can access param[:customer] the same as you would if it was coming from a normal form submission. I had to be sure and specify it was a PUT request when I sent it in, which I didn't realize was as straightforward to do as it is. I monkeyed around with a _method param and all sorts of stuff before realizing I could just tell the HTTPRequest object what kind of request I wanted to make. Duh.

Though this is a specific example right now, I think a large portion of this code should be easy to extract out into an ActiveResouce client base class. I haven't had any more time to hack on this since erubycon, sadly, but this is what I'll be focusing on when next I do. Also, I just now put up a new repo on github to hold this and any other rubyjs_on_rails example code: git:// Enjoy!