O hai!

• State transitions validation.

• State-scoped validations.

• State-scoped lifecycle callbacks (before|after_save, etc)

• ???????

• PROFIT!!!11

As a bonus you get multiple conditions in :if|:unless => [:one, :two, ...] callback and validation options (as in edge Rails).

gem install pipa-statelogic --source http://gems.github.com

Installable as a plugin too.

rdoc.info/projects/pipa/statelogic

Please report via Github issue tracking.

Hint: If you feel like generous today you can tip me at tipjoy.com/u/pisuka

class Order < ActiveRecord::Base
  ...
  statelogic :attribute => :state do # +:state+ is the default value, may be omitted
    # you get methods +unpaid?+ and +was_unpaid?+.
    # may be more than one initial state.
    initial_state 'unpaid' do
      transitions_to 'ready', 'suspended' # won't let you change to wrong states
    end
    state 'ready' do # you get +ready?+, +was_ready?+
      transitions_to 'redeemed', 'suspended'
      validates_presence_of :txref # scoped validations
      before_save :prepare_for_plucking # scoped callbacks
    end
    state 'redeemed' do # likewise
      transitions_to 'suspended'
      validates_presence_of :txref, :redeemed_at, :facility_id # scoped validations
    end
    state 'suspended' do # you guess
      transitions_to 'unpaid', 'ready', 'redeemed'
      validate do |order|
        order.errors.add(:txref, :invalid) if order.txref && order.txref !~ /\AREF/
      end
    end
  end
  ...
end

order = Order.new
order.state = 'wtf'
order.txref = 'orly'
order.valid? # Please note that state transition checks are done during
             # the validation step as well, and the error is added to
             # the model's +errors+ collection on the state column and
             # will appear on your form. Standard ActiveRecord's error
             # message +:inclusion+ is used. Override it with Rails i18n
             # for something more specific if it's to be displayed to user.

Copyright © 2009 Igor Gunko, released under the MIT license