Rails Polymorphic has_many

Question

Using Ruby on Rails, how can I achieve a polymorphic has_many relationship where the owner is always of a known but the items in the association will be of some

Answer 1

Here is the workaround I'm currently using. It doesn't provide any of the convenience methods (collection operations) that you get from real ActiveRecord::Associations, but it does provide a way to get the list of products for a given producer:

class Bicycle < ActiveRecord::Base
  belongs_to :producer
end

class Popsicle < ActiveRecord::Base
  belongs_to :producer
end

class Producer < ActiveRecord::Base
  PRODUCT_TYPE_MAPPING = {
    'bicycle' => Bicycle,
    'popsicle' => Popsicle
  }.freeze
  def products
    klass = PRODUCT_TYPE_MAPPING[self.type]
    klass ? klass.find_all_by_producer_id(self.id) : []
  end
end

Another downside is that I must maintain the mapping of type strings to type classes but that could be automated. However, this solution will suffice for my purposes.