How to type an attribute that returns a model but doesn't use a has_one association

[mpvosseller]

My Foo model has a method called bar that returns a Bar model instance (or nil).

It is technically not a has_one association though because there is not foreign key. Rather the bar method uses some business logic to determine which Bar to return.

In the Foo dashboard, what "type" should I use for the bar attribute?

I found that I can use the "Field::HasOne" with the class_name option but that option is deprecated:

  bar: Field::HasOne.with_options(class_name: "Bar"),

If I omit the class_name option Administrate crashes because (I think) it can't determine the type via reflection.

  bar: Field::HasOne,

Thanks.

[nickcharlton]

I'm not really sure what a good suggestion for this might be, aside from writing a custom field (which, perhaps is too much in this case?).

I will note #2384, though, where we've found other cases where class_name is necessary.