Datamapper DataMapper

Hi,

I'm trying to use edge DataMapper with an edge Rails project where I'm using the position attribute as a primary key on some of my models. I got some strange behavior, and I managed to emulate it in the rb file that's attached (and copy-pasted below). I commented everything, so it should be pretty self-evident.

I dug through is-list to try to figure out what's going wrong, but I didn't get far. I'll try again, but I wanted to post this in the meantime.

Thanks!

require "rubygems"
require "dm-core"
require "dm-is-list"

# Setup DataMapper. I'm using Postgres, but I don't think it matters.

class Question
  include DataMapper::Resource

  property :position, Integer, :key => true

  is :list

  has n, :answers, :child_key => [:question_position]
end

class Answer
  include DataMapper::Resource

  property :question_position, Integer, :key => true
  property :position, Integer, :key => true

  is :list, :scope => [:question_position]

  belongs_to :question, :child_key => [:question_position]
end

Question.auto_migrate!
Answer.auto_migrate!




# Creating a child through an association returns the wrong object.

q1 = Question.create
a1 = q1.answers.create
a2 = q1.answers.create
a3 = q1.answers.create

puts q1.inspect   #=> #<Question @position=1>
puts a1.inspect   #=> #<Answer @question_position=1 @position=1>
puts a2.inspect   #=> #<Answer @question_position=1 @position=2>
puts a3.inspect   #=> #<Answer @question_position=1 @position=2>

puts a1.eql? a2   #=> false
puts a2.eql? a3   #=> true

try_again = Answer.get(1,3)
puts try_again.inspect   #=> #<Answer @question_position=1 @position=3>



# Can't move objects around list.

begin
  try_again.move(:highest)   #=> ERROR:  duplicate key value violates unique constraint "answers_pkey" (DataObjects::IntegrityError)
  rescue DataObjects::IntegrityError
end



# Finally, if the Answer class has any other properties, there's a duplicate key problem on the fourth object made.

q2 = Question.create
20.times do
  q2.answers.create
end   #=> No problem

class Answer
  property :title, String
end
Answer.auto_migrate!

q3 = Question.create
20.times do
  q3.answers.create
end   #=>   ERROR:  duplicate key value violates unique constraint "answers_pkey" (DataObjects::IntegrityError)