避免重复Linq待处理插入？

Question

I can prevent the same object from being added twice , but I still need to reference the pending id to add other related objects.

In the following, some disctinct items in SomeData might want to add the same person twice. I can track that, but I still need to add the distinct item informatio to the pending person. how do i manage this?

   foreach(item i in SomeData)
      {
         var x = dc.People.Where(p.someprop==a...);
         if (x=null)
         { 
           Person p = new P(..);
           dc.People.InsertOnSubmit(p);
         }
         ...
         ...
      }

      dc.Submitchanges()

Answer 1

Basically you need to check to see if the entity is already attached to the context. Here is an example of how you can make this work:

public static void SafeAttachTo<T>(this ObjectContext context, string entitySetName, ref T entity) where T : class {
            ObjectStateEntry entry;
            bool isDetached;

            if (context.ObjectStateManager.TryGetObjectStateEntry(context.CreateEntityKey(entitySetName, entity), out entry)) {
                isDetached = entry.State == EntityState.Detached;
                entity = (T) entry.Entity;
            }
            else
                isDetached = true;

            if (isDetached)
                context.AttachTo(entitySetName, entity);
        }