关于belong_to，has_one，has_many的困惑

Question

I am trying to extend the function of a Shift model in my project. I have two types of shifts Ashift and Bshift, that are immediately related to Shift.

My confusion stems from how to set up the associations in Shift. This is what I have:

I am trying to say that Shift has one or the other dependent shift class, but not both, and also not neither.

class Ashift < ApplicationRecord
  belongs_to :shift
end
class Bshift < ApplicationRecord
  belongs_to :shift
end

class Shift < ApplicationRecord
  has_one :ashift
  has_one :bshift
end

I am sure this is clearly laid out in the association guide but I've read it a couple of times, and I am still subtlety confused.

Does has_one, or has_many, refer to each instance of the model, or the Model class as a whole? Is there a different, or better way of doing this?

Answer 1

use has one and STI readmore about this here

class TheShift < ApplicationRecord
  belongs_to :shift
end

class Ashift < TheShift 
end

class Bshift < TheShift 
end

class Shift < ApplicationRecord
  has_one :theshift
end