rails_3_as_json.rb

# In Rails 3, I wanted to include some additional json values in my data for 
# the jquery ui autocomplete plugin. Overriding to_json() at the model level
# seemed to work on a specific model instance, but not for a collection of 
# model instances. (pretty sure that worked in prior Rails versions)

# Here's the working code:

class PostsController < ApplicationController
  def index
    @posts = Post.all

    respond_to do |format|
      format.html # index.html.erb
      format.json  { render :json => @posts.to_json }
    end
  end

  def show
    @post = Post.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render :json => @post.to_json }
    end
  end
end


class Post < ActiveRecord::Base
	JSON_ATTRS = ['title', 'body']

	def as_json(options = nil)
		attributes.slice(*JSON_ATTRS).merge(:label => title, :value => id)
	end
end

# solution found here:
# *** Synchronizing Core Data With Rails (slide #28) ***
# http://www.slideshare.net/metaskills/synchronizing-core-data-with-rails