Question

我是MVC的新手（来自Web Forms）。我有一个控制器，有两个这样的动作：

Public Function Delete(ByVal id As Nullable(Of Integer)) As ActionResult
    Dim Count As Integer = IModel.DeleteMember(id)
    If Count = 1 Then
        ViewBag.Message = "Member " & id & " was deleted. "
    Else
        ViewBag.Message = "There was a problem deleting the record. "
    End If
    Return RedirectToAction("Members")
End Function

ViewBag未传递给Members视图。为什么呢？

Answer 1

ViewBag允许您将数据存储在将在相应视图中使用的控制器操作中。这假定操作返回视图并且不重定向。仅在当前请求期间生活。

TempData允许您存储为重定向而存活的数据。在内部，它使用Session作为烘焙商店，只是在重定向之后，数据被自动驱逐。

所以你应该使用tempData

If Count = 1 Then
    TempData["Message"] = "Member " & id & " was deleted. "
Else
    TempData["Message"] = "There was a problem deleting the record. "

Return RedirectToAction("Members")

或者返回一个视图，而不是重定向......

Dim Count As Integer = IModel.DeleteMember(id)
If Count = 1 Then
    ViewBag.Message = "Member " & id & " was deleted. "
Else
    ViewBag.Message = "There was a problem deleting the record. "
End If

Return View("Members")

参考：ViewBag, ViewData and TempData

Answer 2

也许这会奏效：

Public static String msg
...
Public Function Delete(ByVal id As Nullable(Of Integer)) As ActionResult
    Dim Count As Integer = IModel.DeleteMember(id)
    If Count = 1 Then
        msg = "Member " & id & " was deleted. "
    Else
        msg = "There was a problem deleting the record. "
    End If
    Return RedirectToAction("Members")
End Function

Public Function Members() As ActionResult
    ViewBag.Message = msg;
    Return View()
End Function

由于您定义了ViewBag变量，然后定义了RedirectToAction，ViewBag值将丢失，并且不会显示给会员视图。

当视图明确指定时，ViewBag未被视图看到

2 个答案: