Reactor - Controlled reactions on ActiveRecord callbacks

ActiveRecord Reactors provide a defined way to react on default or custom Active Record callbacks. You may think of them as Observers without the magic, and without the hassle.

Install

# In your Gemfile
gem 'activerecord-reactor'

Usage

Define a custom reactor class, where you would use an Observer:

class YummyReactor < ActiveRecord::Reactor
  after_create(record)
    puts "Yummy, #{record.color} #{record.class.name} created!" if record.is_a?(Fruit)
  end
end

Connect your models to the reactor:

class Fruit < ActiveRecord::Base
  attr_accessor :peel
  
  reactor :yummy

  def color; end
end

You can also use custom model callbacks:

class Tidy < ActiveRecord::Reactor
  def before_peel(record)
    record.wash!
  end

  def after_peel(record)
    GarbageCollector.dispose(record.peel)
  end
end

class Banana < Fruit
  # Use instead of define_model_callbacks if you want to register
  # the callback with reactors
  define_reactor_callbacks :peel

  # You can use the actual class if you do not want the reactor name end with 'Reactor'
  reactor Tidy

  def color
    'yellow'
  end

  def peel!
    run_callbacks :peel do
      self.peel = Object.new
    end
  end
end

Finally, you can temporarily shutdown any reactions on a reactor:

class Apple < Fruit; end

YummyReactor.scram do
  Apple.create! # hide this one from YummyReactor
end