Elegantly selecting attributes from has_many :through join models in Rails

Question

I\'m wondering what the easiest/most elegant way of selecting attributes from join models in has_many :through associations is.

Lets say we have Items, Catalogs, and Cat

Answer 1

You can do something like this:

# which is basically same as your "frustrating way" of doing it
@item.catalog_items.find_by_catalogue_id(@item.catalogs.first.id).position

Or you can wrap it into in an instance method of the Item model:

def position_in_first_catalogue
  self.catalog_items.find_by_catalogue_id(self.catalogs.first.id).position
end

and then just call it like this:

@item.position_in_first_catalogue