Ruby on Rails 3 (3.1) ActiveModel Associations (tableless nested models)

Question

How to impliment ActiveModel associations (tableless nested models)?

For example:

book has many chapters

With ActiveRecord I would

Answer 1

With rails versions >= 2.3.x you can use the activerecord-tableless gem. With that gem you can have associations and validations without a database.

Update

I have been added as author to the gem and I have updated the gem to support newer Rails versions. So now we can have tableless models with associations in Rails versions >= 2.3