require 'rubygems'
require 'dm-core'
require 'dm-is-remixable'

module Comment
  include DataMapper::Resource
  is :remixable

  property :id,         Integer, :key => true, :serial => true
  property :body,       String
end

class Article
  include DataMapper::Resource

  remix 1, :comments
end

DataMapper.setup(:default, 'sqlite3::memory:')
c = Article.new({
      :body  => 'hello there',
    })
p c

# /usr/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/resource.rb:622:in `assert_valid_model': Article must have a key. (DataMapper::IncompleteResourceError)
#       from /usr/lib/ruby/gems/1.8/gems/dm-core-0.9.11/lib/dm-core/resource.rb:609:in `initialize'
#       from a1.rb:20:in `new'
#       from a1.rb:20