Allow an Active Record or MongoMapper model to act as a finite state machine just as the popular plugin acts_as_state_machine but with many enhancements such as the possibility to have multiple states per object.

It can work together with the classic act_as_state_machine on the same project but both cannot be used at the same time for one given Active Record model. Moreover, simple_state_machine work standalone and doesn't require acts_as_state_machine.

You also get magic methods to check current state and a way to revert to previous state in database (or initial value for a new record) if something went wrong.

• Ruby 1.8.7 or 1.9.2

• gem "active_record", ">= 3.0.0"
• gem "mongo_mapper", "~> 0.9.0"

• With ActiveRecord

      require "simple_state_machine/active_record"
  
      class Chicken < ActiveRecord::Base
        state_machine :user_state, [:pending, :active, :removed, :on_hold]
        state_machine :validation_state, [:waiting, :reviewed, :validated, :invalid]
        def user_activate!
          return false if !user_state_pending?
          self.user_state = :active
          save! rescue user_state_revert
          user_state_active?
        end
      end
  
      # And then you can do:
  
      c = Chicken.create # c.user_state = :pending
      c.user_activate! # c.user_state = :active
  

• With MongoMapper

      require "simple_state_machine/mongo_mapper"
  
      class Chicken
        include MongoMapper::Document
        plugin SimpleStateMachine::MongoMapper
  
        state_machine :user_state, [:pending, :active, :removed, :on_hold]
        state_machine :validation_state, [:waiting, :reviewed, :validated, :invalid]
        def user_activate!
          return false if !user_state_pending?
          self.user_state = :active
          save! rescue user_state_revert
          user_state_active?
        end
      end
  
      # And then you can do:
  
      c = Chicken.create # c.user_state = :pending
      c.user_activate! # c.user_state = :active
  

SimpleStateMachine is Copyright © 2010-2011 Openhood.com It is free software, and may be redistributed under the terms specified in the MIT-LICENSE file.