Form with two different nested models which exclude each other

Question

I have a form for one model with a couple of input boxes and one dropdown box where type ( TypeA and TypeB ) of the model can be picked. Let's say models are something like this:

// car has columns name and country
class Car < ActiveRecord::Base
end

// has columns a_property_1 and a_property2
class TypeAProperties < ActiveRecord::Base
    belongs_to :cars
end

// has columns b_property_1 and b_property2
class TypeBProperties < ActiveRecord::Base
    belongs_to :cars
end

After user opens form, by default there should be displayed fields for name, country, dropdown box with TypeA selected, a_property_1 and a_property2.

If user navigates to dropdown box and selects TypeB , a_property_1 and a_property2 should disappear from screen, and b_property_1 and b_property2 should appear on screen. So, TypeAProperties and TypeBProperties are created depending on selected value from drop down box. Car can have only one property, A or B.

Any ideas how to handle this situation? I am a little bit stuck with this. Thank you.

Answer 1

I believe you should do vise versa, so:

class Cars < ActiveRecord::Base
   belongs_to :car_type, polymorphic: true
end

and in type classes

class TypeAPropertySet < ActiveRecord::Base
   has_one :car, as: :car_type # or has_many
end

class TypeBPropertySet < ActiveRecord::Base
   has_one :car, as: :car_type # or has_many
end

Please refer to the document on the rails polymorphism. So then you be able to use Car s properties, along with the car_type in the form.