Rails: Create association if none is found to avoid nil errors

Question

I have an application where my users can have a set of preferences. Both are stored as ActiveRecord-models as follows:

class User < AR::Base
   has_one :p         


        

Answer 1

or simply

class User < ApplicationRecord
   has_one :preference_set

   def preference_set
     super || build_preference_set
   end
end

This works because ActiveRecord defines the association method in a mixin.