Casting ActiveRecord scopes or instances to ActiveType extended model classes

When working with ActiveType you will often find it useful to cast an ActiveRecord instance to its extended ActiveType::Record variant.

Starting with active_type 0.4.0 Show archive.org snapshot you can use ActiveType.cast for this:

class User < ActiveRecord::Base
  ...
end

class SignUp < ActiveType::Record[User]
  ...
end

user = User.find(1)
sign_up = ActiveType.cast(user, SignUp)
sign_up.is_a?(SignUp) # => true

This is basically like ActiveRecord#becomes Show archive.org snapshot , but with fewer bugs and more consistent behavior.

You can also cast an entire relation (scope) to a relation of an ActiveType::Record:

adult_users = User.where('age >= 18')
adult_sign_ups = ActiveType.cast(adult_users, SignUp)
sign_up = adult_sign_ups.find(1)
sign_up.is_a?(SignUp) # => true