c# - 使用外键删除 LINQ 中的记录 - 无效强制转换异常

Question

我有一个简单的数据库:

ARTICLE
----------
ArticleId (PK),
ArticleTitle
..other stuff...

USER-ARTICLE
------------
ArchiveId (PK),
UserId,
ArticleId
..other stuff...

articleId 是外键。

我希望能够使用以下代码通过 UserArticleId 删除用户文章行，

UserArticle myobjtodelete = PersonalArchiveDb.UserArticles.Single(ua => ua.ArchiveId == 3);
PersonalArchiveDb.UserArticles.DeleteOnSubmit(myobjtodelete);
PersonalArchiveDb.SubmitChanges();

^{(是的，我知道我可以在删除中执行语句而不是检索对象，这是为了调试目的以确保对象确实存在 - 它确实存在。)}

当调试器遇到 SubmitChanges() 行时，我收到一个运行时错误:

Specified cast is not valid.

这是堆栈跟踪，

at System.Data.Linq.IdentityManager .StandardIdentityManager .SingleKeyManager`2.TryCreateKeyFromValues(Object[] values, V& v) at System.Data.Linq.IdentityManager.StandardIdentityManager.IdentityCache`2.Find(Object[] keyValues) at System.Data.Linq.IdentityManager.StandardIdentityManager.Find(MetaType type, Object[] keyValues) at System.Data.Linq.CommonDataServices.GetCachedObject(MetaType type, Object[] keyValues) at System.Data.Linq.ChangeProcessor.GetOtherItem(MetaAssociation assoc, Object instance) at System.Data.Linq.ChangeProcessor.BuildEdgeMaps() at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode)
at System.Data.Linq.DataContext.SubmitChanges() at Driver_SOC_ASO.Controls.PersonalArchive.ArchiveListing.grdArchive_RowDeleting(Object sender, GridViewDeleteEventArgs e) in C:\work\Driver.Net\Driver-SOC-ASO\Driver-SOC-ASO\Controls\PersonalArchive\ArchiveListing.ascx.cs:line 78 at System.Web.UI.WebControls.GridView.OnRowDeleting(GridViewDeleteEventArgs e) at System.Web.UI.WebControls.GridView.HandleDelete(GridViewRow row, Int32 rowIndex) at System.Web.UI.WebControls.GridView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup) at System.Web.UI.WebControls.GridView.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.GridView.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

我很茫然，有什么想法吗？

Answer 1

这可能是这个 bug 的一个例子，Microsoft 表示已在 .NET 4.0 中修复。