use state_machine

use_state_machine.rb

# sample class
class Book < ActiveRecord::Base
  attr_accessible :author, :status, :title

  state_machine :status, :initial => :draft do

    state :draft, :public, :suspending, :archived

    state :draft do
      def published?; false end
    end

    state :public, :suspending, :archived do
      def published?; true end
    end

    event :rewrite do
      transition :public => :draft
    end

    event :publish do
      transition :draft => :public
    end

    event :suspend do
      transition :public => :suspending
    end

    event :archive do
      transition :suspending => :archived
    end
  end

end

# usage
irb(main):024:0> b = Book.new
=> #<Book id: nil, title: nil, author: nil, status: "draft", created_at: nil, updated_at: nil>
irb(main):070:0> b.published?
=> false
irb(main):025:0> b.publish
=> true
irb(main):026:0> b.status
=> "public"
irb(main):074:0> b.published?
=> true
irb(main):027:0> b.rewrite
irb(main):028:0> b.status
=> "draft"
irb(main):030:0> b.status_events
=> [:publish]
irb(main):031:0> b.archive
=> false
irb(main):032:0> b.status
=> "draft"
irb(main):033:0> b.publish
=> true
irb(main):034:0> b.archive
=> false
irb(main):035:0> b.status
=> "public"
irb(main):036:0> b.suspend
irb(main):037:0> b.status_events
=> [:archive]
irb(main):038:0> b.archive
irb(main):039:0> b.status
=> "archived"
irb(main):040:0> b.published?
=> true