@@ -1,6 +1,6 @@ = Stalker -Rails micro-plugin (35 lines) which allows models to observe each other. +Rails micro-plugin (38 lines) which allows models to observe each other. == Install @@ -35,6 +35,27 @@ Now let's see what happens. == What happened? The stalker class (Idiot) now has magical class methods (such as before_[stalked_class]_save(stalked_instance), after_[stalked_class]_validate(stalked_instance), etc) for reacting to stalked class's callbacks. Keep in mind they're class methods, hence the class << self thingie. As an argument these methods get the reference to the instance of the stalked class. This way you can alter the object or just extract information from it. +== Group your victims! +If you want to stalk multiple models with same responses, it's easy to do using :group option. + + class Celebrity < ActiveRecord::Base + end + + class Politician < ActiveRecord::Base + end + + class Idiot < ActiveRecord::Base + stalk Celebrity, Politician, :group => :victim + + def self.before_victim_save(victim) + if victim.is_a?(Politician) + poke(victim) + else + bite(victim) + end + end + end + == Why? Sometimes you want model A to notify model B if something happens to it, so that model B could react. It's useful if it's concern of model B, like it has to update its records. If you have Product model that needs to decrement count of products when Order has been placed, you'd want Order model to notify Product model about the fact that it's been placed. Product can then decrement item count in itself. README.rdoc @@ -7,18 +7,21 @@ module Stalker def instance; end def stalk(*models) + options = models.extract_options! models.flatten! models.map do |m| - m.add_stalker!(self) + m.add_stalker!(self, options) end end - def add_stalker!(klass) + def add_stalker!(klass, options = {}) + stalkee = options[:group] || self.name.underscore establish_channels = "" + for callback in ActiveRecord::Callbacks::CALLBACKS mole = :"notify_#{klass.to_s.underscore}_#{callback}" - notify_stalker = :"#{callback.split('_', 2).join("_#{self.name.underscore}_")}" + notify_stalker = :"#{callback.split('_', 2).join("_#{stalkee.downcase}_")}" self.send(callback, mole) establish_channels += <<-end_code def #{mole} lib/stalker.rb b28273084ed790da68374d72f60c14c9a5bfc73d Maxim Chernyak max@bitsonnet.com http://github.com/maxim/stalker/commit/4869bbb69ce51233031a904d32f9cf291dc2b6bb 4869bbb69ce51233031a904d32f9cf291dc2b6bb 2009-04-10T00:00:53-07:00 2009-04-10T00:00:53-07:00 Stalked models can now be grouped. See README for details. 3ef06c5f1748f7d12a6142959459adac9c5425f7 Maxim Chernyak max@bitsonnet.com