private void UserProductsChanged(object sender, NotifyCollectionChangedEventArgs e)        {
           NotifyOfPropertyChange(() => UserProducts);
        }

        public IEnumerable<Product> UserProducts        {            get { return User.UserProducts.Select(up => up.Product); }        }

        public void AddProduct(Product product)        {            var userProduct = new UserProduct                                  {                                      ProductId = product.ProductId                                  };            EntityAspect.EntityManager.AddEntity(userProduct);             userProduct.UserId = UserId;        }

This way the product is getting resolved before I attach it to the user (Which fires off the collection event)

        public void AddProduct(Product product)        {            var userProduct = new UserProduct                                  {                                      UserId = UserId,
                                      ProductId = product.ProductId                                   };            EntityAspect.EntityManager.AddEntity(userProduct);        }

I have tried it with or without setting ProductId = product.ProductId

User.EntityAspect.IsNullOrPendingEntity = false
User.UserProducts IsPendingEntityList = false

What is very interesting is, sometimes if I set breakpoint on the AddEntity line, wait a few seconds, then let it execute, it works.

The detached entity is trying to resolve something and it is failing initially.

This is the stacktrace:

   at IdeaBlade.EntityModel.EntityAspect.SetValueWithChangeNotification(DataEntityProperty property, Object newValue)
   at IdeaBlade.EntityModel.EntityManager.GenerateId(Object entity, DataEntityProperty entityProperty)
   at IdeaBlade.EntityModel.EntityManager.UpdatePkIfNeeded(EntityAspect aspect)
   at IdeaBlade.EntityModel.EntityManager.AttachEntityAspect(EntityAspect aspect, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.<>c__DisplayClass60.<AddOrAttachRelatedEntities>b__5d(EntityAspect w)
   at IdeaBlade.Core.EnumerableFns.ForEach[T](IEnumerable`1 items, Action`1 action)
   at IdeaBlade.EntityModel.EntityManager.AddOrAttachRelatedEntities(EntityAspect wrapper, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AttachEntityAspect(EntityAspect aspect, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AttachEntity(Object entity, EntityState entityState)
   at IdeaBlade.EntityModel.EntityManager.AddEntity(Object entity)
   at Spindlemedia.Models.Security.User.AddProduct(Product product)

At the time of the exception:

UserProduct is successfully added to the manager, with a generated id of -100 and it is in the Added State

UserProduct.Product.EntityAspect.IsNullOrPendingEntity = true
UserProduct.User.EntityAspect.IsNullOrPendingEntity = false

They are both in the same entity manager, so I'm not sure what the issue is.

Thoughts?