Datamapper DataMapper

It's been about a week since I've updated DM code - I'm on deadline to finish a project! :) That being said, when you do something like this:

class User
  include DataMapper::Resource
  property  :id, Integer, :serial => true
  has n, :sit
end

class ParentTable
  include DataMapper::Resource
  property :id,  Integer, :serial => true
  property :user_id,  Integer, :index => true
  property :type,   String, :index => true
end

class Sit < ParentTable; end

And then you run the following code:

u = User.new
u.save
u_sit = u.sits.new

u_sit.user_id is nil. However, when you run u_sit = u.sits.create, u_sit.user_id is the proper number. I would expect the method new to act as the method create and populate the user_id field with the id of user.