DM #attributes

gistfile1.rb

require 'rubygems'
require 'dm-core'
require 'dm-migrations'

DataMapper.setup(:default, 'sqlite::memory:')

class Product
  include DataMapper::Resource

  property :id,          Serial
  property :category,    String
  property :subcategory, String

  def categories
    [self.category, self.subcategory]
  end

  def categories=(categories)
    self.category = categories.first
    self.subcategory = categories.last
  end
end

Product.auto_upgrade!

product = Product.new(:categories => ['Foo', 'Bar'])

# Outputs only resource defined properties
p product.attributes