Multisite Shop Example w/MongoDB

multisite.rb

# Order class
# see http://www.slideshare.net/wonko/persisting-dynamic-data-with-mongodb-and-mongomapper

class Order
  include MongoMapper::Document
  key :order_id, String

  class << self
    def for_site(site)
      klass = Class.new(self)
      klass.order_fields = site.order_fields
      Object.const_set("OrderForSite#{site.id}", klass)
      klass
    end

    def order_fields=(fields)
      fields.each do |field|
        key field, String
      end
    end
  end
end

# current_site.order_fields
# => ["field1", "field2"]
# @order = Order.for_site(current_site).new