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我正在尝试按照本教程将乐观并发添加到我的应用程序中。

不幸的是，该应用程序就像我没有改变任何东西一样工作。我打开两个浏览器，在两个浏览器中都编辑同一行，覆盖相同的值并将其放在第一个，而另一个根本没有响应。我将保存第二个，但仍然没有警告。我试图逐步完成它，并使用编辑按钮并在保存时RowVersion改变了我。只有SaveChanges()不抛出异常。

SQL 服务器：

CREATE TABLE [dbo].[Table] (
    [Id]         INT            IDENTITY (1, 1) NOT NULL,
    [RowVersion] ROWVERSION     NULL,
...

模型：

public partial class Table
{
    public int Id { get; set; }

    [Column(TypeName = "timestamp")]
    [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
    [MaxLength(8)]
    public byte[] RowVersion { get; set; }

控制器：

[HttpPost]
public ActionResult Table_Edit([Bind(Include = "Id,RowVersion")]Table tab)
{
    try
    {
        if (ModelState.IsValid)
        {
            db.Entry(tab).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
    }
    catch (DbUpdateConcurrencyException ex)
    {
        var entry = ex.Entries.Single();
        Table clientValues = (Table)entry.Entity;
        Table  databaseValues = (Table )entry.GetDatabaseValues().ToObject();
        //changed column
        if (databaseValues.Column_5 != clientValues.Column_5)
            ModelState.AddModelError("Name", "Current value: "
                + databaseValues.Column_5);

        ModelState.AddModelError(string.Empty, "The record you attempted to edit "
            + "was modified by another user after you got the original value. The "
            + "edit operation was canceled and the current values in the database "
            + "have been displayed. If you still want to edit this record, click "
            + "the Save button again. Otherwise click the Back to List hyperlink.");
        tab.RowVersion = databaseValues.RowVersion;
    }

    catch (DataException /* dex */)
    {
        //Log the error (uncomment dex variable name after DataException and add a line here to write a log.
        ModelState.AddModelError(string.Empty, "Unable to save changes. Try again, and if the problem persists contact your system administrator.");
    }
    return View(tab);
}
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