class Product < ActiveRecord::Base
  belongs_to :buyable, :polymorphic => true
end


class Wine < ActiveRecord::Base
  has_one :product, :as => :buyable
end

# this works
@wine = Wine.find(:first)
@wine.product.attribute_x -> "the value as expected"

# how do i get this one to work?
@product = Product.find(:first)
@product.wine.attribute_x -> undefined method wine