Why polymorphic association doesn't work for STI if type column of the polymorphic association doesn't point to the base model of STI?

Question

I have a case of polymorphic association and STI here.

# app/models/car.rb
class Car < ActiveRecord::Base
  belongs_to :borrowable, :polymorphic => tru         


        

Answer 1

I agree with the general comments that this ought to be easier. That said, here is what worked for me.

I have a model with Firm as the base class and Customer and Prospect as the STI classes, as so:

class Firm
end

class Customer < Firm
end

class Prospect < Firm
end

I also have a polymorphic class, Opportunity, which looks like this:

class Opportunity
  belongs_to :opportunistic, polymorphic: true
end

I want to refer to opportunities as either

customer.opportunities

or

prospect.opportunities

To do that I changed the models as follows.

class Firm
  has_many opportunities, as: :opportunistic
end

class Opportunity
  belongs_to :customer, class_name: 'Firm', foreign_key: :opportunistic_id
  belongs_to :prospect, class_name: 'Firm', foreign_key: :opportunistic_id
end

I save opportunities with an opportunistic_type of 'Firm' (the base class) and the respective customer or prospect id as the opportunistic_id.

Now I can get customer.opportunities and prospect.opportunities exactly as I want.