c# - LINQ 冲突 - 行未找到或未更改

Question

我从我的用户那里收到相当频繁的错误报告，一个典型的错误报告是:

Error Message: Row not found or changed.
Stack Trace:
at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) 
at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) 
at Controls_Article_ArticleViewer.LoadArticle() 
at ViewTutorial.Page_Load(Object sender, EventArgs e) 
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

(如果需要，我可以提供更多细节)。该函数 LoadArticle() 中唯一直接的 LINQ 代码是:

    using (MainContext db = new MainContext())
    {
        var q = (
                    from A in db.tblArticles
                    where A.ID == this.ArticleID && A.IsDeleted == false
                    select A
                ).SingleOrDefault();
        if (q == null)
        {
            Server.Transfer("~/404.aspx");
            Context.Response.End();
        }
        else
        {
            // Cache expired for HTML generation
            if (q.HTMLLastGenerated.AddSeconds(Settings.ArticleRegenHTMLCacheSecs) < DateTime.Now)
            {
                q.Body = ArticlesCommon.Markdown(q.MarkupBody);
                q.HTMLLastGenerated = DateTime.Now;
            }

            q.Views++;
            q.LastView = DateTime.Now;
            db.SubmitChanges();

            // Set passbakcs
            this.AuthorID = q.AuthorID;
            this.Anchor = q.Anchor;
            this.SectionID = q.SectionID;
            this.Views = q.Views;
            this.DatePublished = q.Date;
            ArticleAnchor = q.Anchor;
            ArticleAuthorID = q.AuthorID;

            // Get the latest edit
            ArticleEdit LatestEdit = ArticleEditCommon.GetLatestEdit(this.ArticleID);
            // An edit exists!
            if (LatestEdit.ID != 0)
            {
                this.Description = LatestEdit.Description;
                this.ArticleTitle = LatestEdit.Title;
                ArticleBody.Text = LatestEdit.Body;
                ArticleH1.Text = ArticleTitle;
            }
            // No edits
            else
            {
                this.Description = q.Description;
                this.ArticleTitle = q.Title;
                ArticleBody.Text = q.Body;
                ArticleH1.Text = ArticleTitle;
            }

            // Get toal comments
            TotalComments = (from C in db.tblComments where C.IsDeleted == false && C.Anchor == ArticleAnchor select new { C.ID }).Count();

            // Get author details
            var qq = (from A in db.tblForumAuthors where A.Author_ID == ArticleAuthorID select new { A.Username }).Single();
            AuthorUsername = qq.Username;
        }
    }

LoadArticle 中可能还有其他函数引用了运行 LINQ 的方法，但我猜测堆栈跟踪的结果会有所不同，所以上面的代码是原因。

关于什么会导致这种情况的任何想法？数据冲突？通常如何解决此类错误？

有什么想法会导致这种情况吗？

Answer 1

我发现 L2S 中的更新检查机制是一种负担且毫无帮助。如果您需要并发保护，那么您可能应该将它们留在里面。但就我而言，免除检查并让最后一个进来的人保留他的编辑对我来说已经足够了。为此，我禁用了所有专栏的所有更新检查，尽管您可能有理由更加挑剔。为此，请在定义属性时使用 ColumnAttribute 的 UpdateCheck 属性:

[Column(Storage="lastView", Name="LastView", 
 DbType="datetime", UpdateCheck=UpdateCheck.Never)]
public DateTime LastView { ... }

话虽如此，我认为 sqlmetal/dbml 中没有任何工具可以为您执行此操作，因此您必须自己生成实体类(无论如何这不是一个坏主意 - 非常强大)。