AASM improvements

05Dec07

While using great acts_as_state_machine plugin at work I needed to make some improvements to it. This example illustrates new :log_transitions option to acts_as_state_machine directive and how it can be used to audit transitions to action_history_items table – I like to have an action history log for objects that travel by states.
I’d be happy to publish my improvements but don’t know yet in what form.

class ExpenseClaim < ActiveRecord::Base
  has_many :action_history, :class_name => 'ActionHistoryItem', :as => :document,
    :order => 'id desc'

  acts_as_state_machine :initial => States::DRAFT, :log_transitions => true

  state States::DRAFT, :owner => Roles::AUTHOR
  state States::MANAGER_APPROVAL_REQUIRED, :owner => Roles::APPROVING_MANAGER
  state States::REJECTED_BY_FINANCE, :owner => Roles::APPROVING_MANAGER

  #...
  event :send_for_manager_approval do
    transitions :from => States::DRAFT, :to => States::MANAGER_APPROVAL_REQUIRED
    transitions :from => States::REJECTED_BY_MANAGER,
      :to => States::MANAGER_APPROVAL_REQUIRED
  end

  event :approve do
    transitions :from => States::MANAGER_APPROVAL_REQUIRED,
      :to => States::FINANCE_APPROVAL_REQUIRED

    transitions :from => States::FINANCE_APPROVAL_REQUIRED,
      :to => States::APPROVED

    transitions :from => States::REJECTED_BY_FINANCE,
      :to => States::FINANCE_APPROVAL_REQUIRED
  end

  #...
  def log_transition(from, to, event, opts)
    user = self.updated_by
    raise "user is not set" if user.nil?
    as_role = self.class.states_table[from].opts[:owner]
    action_history << ActionHistoryItem.new({:from_state => from.to_s,
      :to_state => to.to_s, :action => event.to_s, :user_id => user.id,
      :as_role => as_role.to_s, :at => Time.now})
  end
#...
end

Update

Here’s the patch mentioned: http://pastie.caboo.se/151469, looks to be perfect way to publish it for now )

More info

Acts as State Machine:
http://rubyi.st/2006/1/21/acts-as-state-machine

Ruby on Rails Finite State Machine Plugin: acts_as_state_machine >> rails symphonies:
http://rails.aizatto.com/2007/05/24/ruby-on-rails-finite-state-machine-plugin-acts_as_state_machine/

Filed under: acts_as_state_machine, rails, ruby   |  6 Comments