acts as state machine models

Saturday, 27 March 2010 19:42
// description of your code here


class Something < ActiveRecord::Base



  # Validations

  validate :validate_state_change



  # State Machine States

  acts_as_state_machine :initial => :new

  state :new

  state :enabled,   :after => :after_enabled

  state :disabled,  :after => :after_disabled



  # State Machine Events

  event :enabled do

    transitions :from => :new,      :to => :enabled

    transitions :from => :disabled, :to => :enabled

  end

  

  event :disabled do

    transitions :from => :new,      :to => :disabled

    transitions :from => :enabled,  :to => :disabled

  end



  # Instance Methods

  def validate_state_change

    return if new_record?

    old = self.class.find(id)

    old_state = old.state

    new_state = self.state

    self.state = old_state

    if old_state != new_state

      begin

        if self.method("#{new_state}!").call != true

          errors.add(:state, "cannot transition from #{old_state} to #{new_state}")

        end

      rescue NameError

      end

      self.state = new_state

    end

  end

end