gistfile1.rb

user.rb

has n, :usage_permissions
  has n, :domains, :through => :usage_permissions, :mutable => true # workaround XXX http://datamapper.lighthouseapp.com/projects/20609/tickets/485-has-n-through-does-not-allow-saving-of-model
  has n, :subdomains


domain.rb

has n, :usage_permissions
  has n, :users, :through => :usage_permissions, :mutable => true # workaround XXX http://datamapper.lighthouseapp.com/projects/20609/tickets/485-has-n-through-does-not-allow-saving-of-model
  belongs_to :owner, :class_name => "User"


usage_permission.rb

 belongs_to :user
    belongs_to :domain



steps:

@user = User.first
@domain = Domain.create
    @domain.owner = @user
    @domain.users = [@user]
    @domain.name = "domenaX"
    @subdomain = Subdomain.new( :name => "SubDomenaDomeny", :user => @user, :domain => @domain )
    @domain.save!

and....

NoMethodError: undefined method `attach_parent' for #<DataMapper::Associations::RelationshipChain:0x7fa5d0d6d490>     
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:302:in `save_resource'                                                                                                                 
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/relationship.rb:172:in `with_repository'                                                                                                              
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/support/kernel.rb:6:in `repository'          
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core.rb:181:in `repository'                       
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/repository.rb:44:in `scope'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core.rb:181:in `repository'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/support/kernel.rb:6:in `repository'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/relationship.rb:172:in `with_repository'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:298:in `save_resource'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:210:in `save'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/lazy_array.rb:391:in `each'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/lazy_array.rb:391:in `send'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/lazy_array.rb:391:in `method_missing'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/collection.rb:638:in `method_missing'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:309:in `send'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:309:in `method_missing'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/associations/one_to_many.rb:210:in `save'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/resource.rb:286:in `hookable__save_nan_before_advised'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/resource.rb:286:in `each'
        from /usr/local/lib/ruby/gems/1.8/gems/dm-core-0.9.8/lib/dm-core/resource.rb:286:in `hookable__save_nan_before_advised'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/hook.rb:294:in `save'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/hook.rb:292:in `catch'
        from /usr/local/lib/ruby/gems/1.8/gems/extlib-0.9.9/lib/extlib/hook.rb:292:in `save'
        from (irb):4