DetailView错误：对象引用未设置为对象的实例

Question

我正在尝试更新用户信息并获取以下错误：

对象引用未设置为 对象的实例。描述：AN 未处理的异常发生在 执行当前的网络 要求。请查看堆栈跟踪 有关错误的更多信息 它起源于代码。

例外详细信息： system.nullreferenceException：对象 引用未设置为一个实例 对象。

源错误：

第20行：'不可否认 构造函数第21行：第22行：
user.email= 直接广播（E.NewValues（0），字符串） 第23行：User.commer.comment= 直播（E.NewValues（1），String） 第24行：user.isapproved= cbool（e.newvalues（2））

.vb代码是：

Protected Sub UserInfo_ItemUpdating(ByVal sender As Object, ByVal e As DetailsViewUpdateEventArgs)
        'Need to handle the update manually because MembershipUser does not have a
        'parameterless constructor  

        user.Email = DirectCast(e.NewValues(0), String)
        user.Comment = DirectCast(e.NewValues(1), String)
        user.IsApproved = CBool(e.NewValues(2))

        Try
            ' Update user info:
            Membership.UpdateUser(user)

            ' Update user roles:
            UpdateUserRoles()

            UserUpdateMessage.Text = "Update Successful."

            e.Cancel = True
            UserInfo.ChangeMode(DetailsViewMode.[ReadOnly])
        Catch ex As Exception
            UserUpdateMessage.Text = "Update Failed: " + ex.Message

            e.Cancel = True
            UserInfo.ChangeMode(DetailsViewMode.[ReadOnly])
        End Try
    End Sub

.

下面是DetailView的.aspx代码：

 Protected Sub UserInfo_ItemUpdating(ByVal sender As Object, ByVal e As DetailsViewUpdateEventArgs)
        'Need to handle the update manually because MembershipUser does not have a
        'parameterless constructor  

        user.Email = DirectCast(e.NewValues(0), String)
        user.Comment = DirectCast(e.NewValues(1), String)
        user.IsApproved = CBool(e.NewValues(2))

        Try
            ' Update user info:
            Membership.UpdateUser(user)

            ' Update user roles:
            UpdateUserRoles()

            UserUpdateMessage.Text = "Update Successful."

            e.Cancel = True
            UserInfo.ChangeMode(DetailsViewMode.[ReadOnly])
        Catch ex As Exception
            UserUpdateMessage.Text = "Update Failed: " + ex.Message

            e.Cancel = True
            UserInfo.ChangeMode(DetailsViewMode.[ReadOnly])
        End Try
    End Sub

.

任何想法如何对此进行排序？

任何帮助将非常感激。

感谢

Answer 1

My first guess, without seeing more code, would be that your user variable is null. Did you set it when you rendered the page? I assume your code above is a postback and so user lost it's value.