automatically calling acts_as_state_machine events on update
I have used acts_as_state_machine in a few client projects and have recently run across a need on a couple of them to allow RESTful updates to change states, easy enough except I want to be able to call the appropriate events and make the proper transitions if they are possible. So I came up with a little bit of code to do just that.
I’m sure there is a more elegant way to do this but I was pressed for time. 
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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 |