Datamapper DataMapper

While experimenting with base model classes, I've found that DM doesn't seem to handle child models which extend from base classes. This scenario is the closest I got it to working - calling "rake dm:db:automigrate" causes an SQL error, as DM tries to create an empty media_bases table. If I add a dummy field to the base class, such as "property :id, Serial", then DM does create a dummy media_bases table, but doesn't create a media_videos table at all.

lib/media.rb

class Media
  class Base

    include DataMapper::Resource

    #property :id, Serial

    def inherited(model)
      model.class_eval do
        property :id,             Serial
        property :title,          String,   :length => 255
        property :description,    Text
        property :created_at,     DateTime
        property :updated_at,     DateTime
        property :deleted_at,     DateTime
        property :created_user,   String, :length => 255
        property :updated_user,   String, :length => 255
        property :deleted_user,   String, :length => 255
        property :filesize,       Integer
      end
    end

  end
end

app/models/media_video.rb

require 'media'
class Media
  class Video < Media::Base

    include DataMapper::Resource

    property :runtime,        Integer
    property :aspect,         String

  end
end