如何在Devexpress XPO上删除旧密钥后创建欺骗密钥？

Question

这是我的产品类别：

  public class Product : XPLiteObject
    {
       public string productId {get;set;}
    }

我使用Gridview来控制数据。当我用productId =“id-5”删除一行时；

gridview1.deleteSelectedRows();

然后添加带有productId =“id -5”的新行；(删除相同的id i)

最后，我说；

unitOfWork1.CommitChanges();

和例外收到:找到了一把假钥匙！

Answer 1

似乎没有从数据库中删除相应的记录。有三个可能的原因：

1. 如果GridView绑定到XPCollection，请确保将XPCollection.DeleteObjectOnRemove属性设置为true。否则，GridView.DeleteSelectedRows方法仅从集合中删除对象；
2. 如果通过GridView绑定到XPCollection，则还需要在执行GridView.DeleteSelectedRows之后执行UnitOfWork.CommitChanges方法。否则，您的更改将不会提交到数据库；
3. 如果产品类使用DeferredDeletionAttribute修饰，则删除该对象将设置相应的布尔列值，但实际上不会从数据库中删除记录。如果是这样的话，有四种解决问题的方法：

- Disable the Deferred Deletion feature at this class by setting the [DeferredDeletionAttribute.Enabled](https://documentation.devexpress.com/#XPO/DevExpressXpoDeferredDeletionAttribute_Enabledtopic) property to false;
- Make sure that objects you are adding are always have a unique value in the key property;
- Instead of creating a new object with the key that is already used, restore the deleted one: [How to restore deleted objects (records)](https://www.devexpress.com/Support/Center/Question/Details/A753)
- You can physically remove from the database records being marked deleted. Use the [Session.PurgeDeletedRecords](https://documentation.devexpress.com/#XPO/DevExpressXpoSession_PurgeDeletedObjectstopic) method for this purpose.

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