如何在ASP.Net MVC中使用post-redirect-get处理并发冲突？

Question

我使用后重定向-获取(PRG)模式来保存ASP.Net MVC2中的实体。控制器方法是“保存”(插入或更新数据库)和“编辑”(检索用户输入)。在'Save‘中，我通过检查实体的'version’列，在保存之前进行修改检查。如果其他人修改了实体，‘版本’列将不匹配，我将向用户发送错误消息。

为了维护错误消息，我在“编辑”方法中使用了ModelState.Merge。这种机制的问题是，用户输入被维护，用户看不到其他用户所做的修改。我通过在添加并发冲突消息之前清除ModelState来避免这个问题。

但我觉得这个解决方案并不是最优的。您将如何处理ASP.Net MVC中的并发冲突？

以下是Edit方法：

    Public Function Edit() As ActionResult
        Dim theevent As AEvents

        If TempData("ModelState") IsNot Nothing And Not ModelState.Equals(TempData("ModelState")) Then
            ModelState.Merge(CType(TempData("ModelState"), ModelStateDictionary))
        End If

        If RouteData.Values.ContainsKey("id") Then
            theevent = NHibGet.EventWithPricingsByCode(RouteData.Values("id"))
        Else
            theevent = New AEvents
        End If

        Dim InputTemplate As New EventEdit With {.EventDate = theevent.EventDate, .EventName = theevent.EventName, .IsActive = theevent.IsActive}
        If theevent.Template IsNot Nothing Then
            InputTemplate.TemplateID = theevent.Template.ID
        End If

        Dim templates As IList(Of SeatTemplates) = NHibGet.TemplatesActive
        ViewData("templates") = templates

        ViewData("eventcode") = theevent.Code
        ViewData("editversion") = theevent.Version

        Return View(InputTemplate)
    End Function

“Save”的代码是这样的：

    Public Function Save(ByVal id As Integer, ByVal UserData As EventEdit, ByVal EditVersion As Integer) As ActionResult
        Dim theevent As AEvents
        If id = 0 Then
            theevent = New AEvents
        Else
            theevent = NHibGet.EventByCode(id)
        End If

        If theevent.Version <> EditVersion Then
            ModelState.Clear()
            ModelState.AddModelError("", "The event is modified by someone else")
            Return RedirectToAction("Edit", New With {.id = id})
        End If

        If Not ModelState.IsValid Then
            TempData("ModelState") = ModelState
            Return RedirectToAction("Edit", New With {.id = id})
        End If

        theevent.EventDate = UserData.EventDate
        theevent.EventName = UserData.EventName
        theevent.IsActive = UserData.IsActive
        theevent.Template = MvcApplication.CurrentSession.Load(Of SeatTemplates)(UserData.TemplateID)

        Using trans As NHibernate.ITransaction = MvcApplication.CurrentSession.BeginTransaction
            MvcApplication.CurrentSession.SaveOrUpdate(theevent)

            Try
                trans.Commit()
            Catch ex As NHibernate.ADOException
                trans.Rollback()
                Throw ex
            End Try
        End Using

        Return RedirectToAction("Edit", New With {.id = theevent.Code})
    End Function

Answer 1

我总是在这种情况下指示用户刷新页面。它还使他有机会检查​​输入的字段值。