Code:

XpVehicleVersionCollection versionColl = new XpVehicleVersionCollection();
            versionColl.Query.Where(versionColl.Query.BrandCode == "ALFA");
            versionColl.Query.Load();

            XpVehicleVersion first = versionColl[0];
            XpVehicleVersion second = versionColl[1];

            //get a car from the first VehicleColl
            XpVehicle car = first.XpVehicleCollectionByXpVehicleVersionID[0];

            //detach it
            first.XpVehicleCollectionByXpVehicleVersionID.DetachEntity(car);

            //and attach it to the second.
            second.XpVehicleCollectionByXpVehicleVersionID.AttachEntity(car);

            versionColl.Save();

I can see the VehicleVersionID change to the one I attach to in 'car'.

But when i do the versionColl.Save() the id get changed back to its originail.

Code:

 //detach it
first.XpVehicleCollectionByXpVehicleVersionID.DetachEntity(car);
      

 //and attach it to the second.
second.XpVehicleCollectionByXpVehicleVersionID.AttachEntity(car);
car.XpVehicleVersionID = first.XpVehicleVersionID.Value;

versionColl.Save();

There is a bug in entity spaces concerning the modified columns in fk references. The AttachEntity sets the FK value, but does not update the modified column collection. So when the save is called, an Object Reference error fires. The work around we use it to set the car.XpVehicleVersionID value before attaching the entity. This causes the car entity to be marked modified and adds an entry to modfied columns.

Code:

//detach it
first.XpVehicleCollectionByXpVehicleVersionID.DetachEntity(car);
      

 //and attach it to the second.
car.XpVehicleVersionID = second.XpVehicleVersionID.Value;
second.XpVehicleCollectionByXpVehicleVersionID.AttachEntity(car);

versionColl.Save();

 Norm