You and me both. This one is a big of a headache to have to wrap my head around.

What sort of case are you questioning? Which end of the `belongs_to`? If the association is a `belongs_to` but is *not* polymorphic, it should fall back to use the `association_primary_key` appended to the method name. So I think that would mean if `post belongs_to :category`, and for whatever reason `category` primary key is `c_id`, the searchable_method_name would be `category_c_id`, and our search method would be `category_c_id_eq`. Right?