To create the table for todo table structure We have to run

rake acts_as_todo:create

to rollback

rake acts_as_todo:roll_back


To create the relation between models and Todo class

class Lesson < ActiveRecord::Base
  aatd
end

class User < ActiveRecord::Base
  work_to_do
end

This will show how the relation works

ruby-1.8.7-p334 :001 > User.create(:name => 'tripurari')
 => #<User id: 1, name: "tripurari", created_at: "2011-06-03 04:49:31", updated_at: "2011-06-03 04:49:31"> 
ruby-1.8.7-p334 :002 > Lesson.create(:name => "should be done")
 => #<Lesson id: 1, name: "should be done", created_at: "2011-06-03 04:50:04", updated_at: "2011-06-03 04:50:04"> 
ruby-1.8.7-p334 :003 > Lesson.create(:name => "Should be done later")
 => #<Lesson id: 2, name: "Should be done later", created_at: "2011-06-03 04:50:23", updated_at: "2011-06-03 04:50:23"> 
ruby-1.8.7-p334 :004 > User.first.todos.create(:work => Lesson.first)
 => #<Todo id: 1, worker_id: 1, worker_type: "User", work_id: 1, work_type: "Lesson", started_at: nil, end_at: nil, created_at: "2011-06-03 04:50:32", updated_at: "2011-06-03 04:50:32"> 
ruby-1.8.7-p334 :005 > Lesson.last.todos.create(:worker => User.first)
 => #<Todo id: 2, worker_id: 1, worker_type: "User", work_id: 2, work_type: "Lesson", started_at: nil, end_at: nil, created_at: "2011-06-03 04:50:39", updated_at: "2011-06-03 04:50:39"> 
ruby-1.8.7-p334 :006 > Todo.first.work
 => #<Lesson id: 1, name: "should be done", created_at: "2011-06-03 04:50:04", updated_at: "2011-06-03 04:50:04"> 
ruby-1.8.7-p334 :007 > Todo.first.worker
 => #<User id: 1, name: "tripurari", created_at: "2011-06-03 04:49:31", updated_at: "2011-06-03 04:49:31">