AlterEgo is my favorite Ruby state machine for the following reasons:
1. It's not dependent on Mongoid - it can be used on plain Ruby objects. 2. It most closely follows the GOF State Pattern because it allows for polymorphic behavior based on state.
Out of the box, AlterEgo doesn't play nicely with Mongoid because it stores state in @state, whereas Mongoid::Document persists with setter methods.
This mixin overrides the AlterEgo's accessor methods for state to allow it to be properly persisted to a database, as well as serialized/unserialized as json, yml, and xml.
As a Ruby Gem
gem install alter-ego gem install alter-ego-mongoid
OR using Rails 3 Bundle
gem 'alter-ego', :require => 'alter_ego' gem 'alter-ego-mongoid', :require => 'alter_ego/mongoid_adapter'
OR as a Rails plugin
script/plugin install git://github.com/wink/alter-ego-mongoid.git
This plugin automatically adds a string field to your model called “state”.
# you'll only need the following two lines if you're NOT using # alter-ego-mongoid as a plugin gem 'alter-ego-mongoid' require 'alter_ego/mongoid_adapter' class Example include Mongoid::Document include AlterEgo # include this first include AlterEgo::MongoidAdapter # Your code here end