Datamapper DataMapper → 1.1

The following code shows the problem:

  require 'rubygems'
  gem 'dm-core', '0.10.1'
  require 'dm-core'

  DataMapper::Logger.new(STDOUT, :debug)
  DataMapper.setup(:default, "mysql://localhost/ts_test")
 
  class Base
    include DataMapper::Resource
    property :id, Serial
    property :type, Discriminator
  end

  class Derived1 < Base
  end

  class Derived2 < Base
    property :extra, Integer
  end

  DataMapper.auto_migrate!
  Derived2.create(:extra => 1)
  Derived2.all.first.extra           # SUCCEEDS
  Base.all.first.extra               # FAILS

Here is the backtrace:

  `+options[:field]+ entry :extra does not map to a property in Base (ArgumentError)`
  dm-core/query.rb:689:in `assert_valid_fields'    
  dm-core/query.rb:680:in `each'
  dm-core/query.rb:680:in `assert_valid_fields'
  dm-core/query.rb:656:in `assert_valid_options'
  dm-core/query.rb:654:in `each'
  dm-core/query.rb:654:in `assert_valid_options'
  dm-core/query.rb:598:in `initialize'
  dm-core/query.rb:343:in `update'
  dm-core/query.rb:359:in `merge'
  dm-core/collection.rb:69:in `reload'
  dm-core/resource.rb:724:in `eager_load'
  dm-core/resource.rb:710:in `lazy_load'
  dm-core/property.rb:596:in `send'
  dm-core/property.rb:596:in `lazy_load'
  dm-core/property.rb:487:in `get'
  dm-core/model/property.rb:200:in `extra'
  from dm-test.rb:24

The problem starts with an STI issue: the first resource returned from Base.all does not have the :extra field loaded. Attempting to access the :extra field triggers a lazy load, which then triggers an eager load. The eager loading code loads the resource as type Base rather than Derived2, and the call to the #extra accessor fails.

So there are at least problems here:

1. All the fields of Derived2 are not properly loaded when accessing via Base.all.first

2. Eager loading via Base.all does not honor the STI type