context.Entry(item).State = EntityState.Unchanged 

            foreach (DbEntityEntry entry in _referencebooksEntities.ChangeTracker.Entries())
                switch (entry.State)
                {
                    case EntityState.Modified:
                        entry.State = EntityState.Unchanged;
                        break;
                    case EntityState.Added:
                        entry.State = EntityState.Detached;
                        break;
                    case EntityState.Deleted:
                        entry.Reload();
                        break;
                }