AWSM - After Workflow State Machine

gistfile1.rb

class Document
  #  ....
  #  ..snip...
  #  ....
  workflow do
    state :created do
      event :scan, :transitions_to => :scanned, :if => Proc.new{|t| !(t.scans.empty?)}
      event :to_edit, :transitions_to => :editing
    end
    state :scanned do
      event :to_edit, :transitions_to => :editing
    end
    state :editing do
      # snip
    end
    state :completed do
      # snip
    end
    state :incomplete do 
      # snip
    end
    state :illegible do
      # snip
    end
    state :checker_rejected do
      # snip
    end
    state :checker_accepted do
      # snip
    end
    state :user_rejected do
      # snip
    end      
    state :user_accepted do
      # snip
    end
    
    on_transition do |from, to, event, *event_args|
      # put all access control validations here
      # *args is basically current_user
      halt! "not authorized" unless Ability.new(event_args[0]).can?(event, self) # sweet - all validations work through this one line.
      AuditTrail.create(:from => from, :to => to, :event => event, :user => event_args[0], :model_name => self.class.to_s, :model_id => self.id)
    end

end