我通过这个工作，发现了以下解决方案。

I worked through this and found the following solution. It works in all the test cases I (and more importantly, my testers!) can think of.

我使用的是 .Attach（） 方法，以及一个TimeStamp列。这工作正常，你第一次将一个特定的主键保存回数据库，但我发现datacontext抛出一个 System.Data.Linq.DuplicateKeyException 无法添加

I am using the .Attach() method on the datacontext, and a TimeStamp column. This works fine for the first time that you save a particular primary key back to the database but I found that the datacontext throws a System.Data.Linq.DuplicateKeyException "Cannot add an entity with a key that is already in use."

我创建的工作是添加一个字典，存储我第一次附加的项目，然后每次我保存我重用该项。

The work around for this I created was to add a dictionary that stored the item I attach the first time around and then every subsequent time I save I reuse that item.

示例代码如下，我想知道是否我错过了任何技巧 - 并发是相当根本的，

Example code is below, I do wonder if I've missed any tricks - concurrency is pretty fundamental so the hoops I'm jumping through seem a little excessive.

希望以下证明是有用的，或者有人可以指示我更好的实现！

Hopefully the below proves useful, or someone can point me towards a better implementation!

private Dictionary<int, Payment> _attachedPayments;

public void SavePayments(IList<Domain.Payment> payments)
    {
        Dictionary<Payment, Domain.Payment> savedPayments =
            new Dictionary<Payment, Domain.Payment>();

        // Items with a zero id are new
        foreach (Domain.Payment p in payments.Where(p => p.PaymentId != 0))
        {
            // The list of attached payments that works around the linq datacontext  
            // duplicatekey exception
            if (_attachedPayments.ContainsKey(p.PaymentId)) // Already attached
            {
                Payment dbPayment = _attachedPayments[p.PaymentId];                    
                // Just a method that maps domain to datacontext types
                MapDomainPaymentToDBPayment(p, dbPayment, false);
                savedPayments.Add(dbPayment, p);
            }
            else // Attach this payment to the datacontext
            {
                Payment dbPayment = new Payment();
                MapDomainPaymentToDBPayment(p, dbPayment, true);
                _dataContext.Payments.Attach(dbPayment, true);
                savedPayments.Add(dbPayment, p);
            }
        }

        // There is some code snipped but this is just brand new payments
        foreach (var payment in newPayments)
        {
            Domain.Payment payment1 = payment;
            Payment newPayment = new Payment();
            MapDomainPaymentToDBPayment(payment1, newPayment, false);
            _dataContext.Payments.InsertOnSubmit(newPayment);
            savedPayments.Add(newPayment, payment);
        }

        try
        {
            _dataContext.SubmitChanges();
            // Grab the Timestamp into the domain object
            foreach (Payment p in savedPayments.Keys)
            {
                savedPayments[p].PaymentId = p.PaymentId;
                savedPayments[p].Timestamp = p.Timestamp;
                _attachedPayments[savedPayments[p].PaymentId] = p;
            }
        }
        catch (ChangeConflictException ex)
        {
            foreach (ObjectChangeConflict occ in _dataContext.ChangeConflicts)
            {
                Payment entityInConflict = (Payment) occ.Object;

                // Use the datacontext refresh so that I can display the new values
                _dataContext.Refresh(RefreshMode.OverwriteCurrentValues, entityInConflict);
                _attachedPayments[entityInConflict.PaymentId] = entityInConflict;

            }
            throw;
        }

    }