models.rb

# /opt/local/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/associations/relationship_chain.rb:49:in `initialize': undefined method `name' for nil:NilClass (NoMethodError)
#   from /opt/local/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/associations/one_to_many.rb:56:in `new'
#   from /opt/local/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/associations/one_to_many.rb:56:in `setup'
#   from /opt/local/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/associations.rb:122:in `has'


class StoreProductInventory

  include DataMapper::Resource

  property :pid, Serial
  property :store_no, Integer, :index => true
  property :product_no, Integer, :index => true
  property :quantity, Integer, :index => true
  property :updated_on, Date, :index => true

  belongs_to :store, :child_key => [:pno], :parent_key => [:store_no]
  belongs_to :product, :child_key => [:pno], :parent_key => [:product_no]

end


class Store

  include DataMapper::Resource

  property :pno, Integer, :key => true
  property :latitude, Float, :index => true
  property :longitude, Float, :index => true
  property :name, String
  property :address_line_1, String
  property :address_line_2, String
  property :postal_code, String, :index => true
  property :city, String, :index => true
  property :telephone, String
  property :fax, String

  has n, :products, :through => :store_product_inventories,
    :child_key => [:product_no],
    :parent_key => [:pno]

end


class Product

  include DataMapper::Resource

  property :pno, Integer, :key => true
  property :price_in_cents, Integer, :index => true
  property :name, String
  property :stock_type, String, :index => true
  property :list_type, String, :index => true
  property :primary_category, String, :index => true
  property :secondary_category, String, :index => true
  property :origin, String
  property :package, String
  property :alcohol_content, Float, :index => true
  property :sugar_content, String, :index => true
  property :producer_name, String

  has n, :stores, :through => :store_product_inventories,
    :child_key => [:store_no],
    :parent_key => [:pno]

end