require 'rubygems'
require 'dm-core'

## Models:

DataMapper.setup(:default, "sqlite3::memory:")

class Key
  include DataMapper::Resource

  property :id,     Serial
  property :key,    Text

  belongs_to :user

  def initialize(opts = {})
    self.key = opts[:key]
  end
end

class User
  include DataMapper::Resource

  property :id,     Serial
  property :name,   Text

  has n, :keys

  def initialize(opts = {})
    self.name = opts[:name]
  end

end

DataMapper.auto_migrate!

## Runtime:

@user = User.create

# Thought this would work:
 @user.keys << Key.create(:key => 'fake key')

# Or this..
  @user.keys.create(:key => 'fake key')

# But keep getting:
  DataObjects::IntegrityError: keys.user_id may not be NULL