ActiveRecord::Observer

This shows how to mimick the behaviour of ActiveRecord::Observer callbacks. The observer is a simple PORO (Plain Old Ruby Object).

The observer, models/bid_observer.rb:

class BidObserver
  def after_create(bid)
    # ...
  end
end

The model, models/bid.rb:

class Bid < ActiveRecord::Base
  include Wisper::Publisher

  validates :amount, :presence => true

  after_create do
    broadcast(:after_create, self)
  end
end

The controller, controllers/bids_controller.rb:

class BidsController < ApplicationController
  def new
    @bid = Bid.new
  end

  def create
    @bid = Bid.new(:amount => 40)
    @bid.subscribe(BidObserver.new)
    @bid.save
  end
end