workflow_mongoid.rb

module Workflow
  module MongoidInstanceMethods
    def load_workflow_state
      self.workflow_state
    end

    def persist_workflow_state(new_value)
      self.workflow_state = new_value
      save!
    end    
  end
  
  def self.included(klass)
    klass.send :include, WorkflowInstanceMethods
    klass.extend WorkflowClassMethods
    if Object.const_defined?(:ActiveRecord) && klass < ActiveRecord::Base
      klass.send :include, ActiveRecordInstanceMethods
      klass.before_validation :write_initial_state
    elsif Object.const_defined?(:Remodel) && klass < Remodel::Entity
      klass.send :include, RemodelInstanceMethods
    elsif Object.const_defined?(:Mongoid) && klass < Mongoid::Document
      klass.send :field, :workflow_state
      klass.send :include, MongoidInstanceMethods
    end
  end  
end