Asp.net 将字段设置为更新DetailView后的值

更新DetailsView并单击DetailView上的更新命令按钮后；我想将其中一个字段设置为“完成”。我做错了什么？请。救命啊。 以下是我的代码：

 Protected Sub Test(sender As Object, e As System.Web.UI.WebControls.DetailsViewUpdatedEventArgs) Handles DetailsView1.ItemUpdated
        If IsPostBack Then
            Dim TextBox7 As TextBox = TryCast(DetailsView1.Rows(0).Cells(0).FindControl("TextBox7"), TextBox)
            TextBox7.Text = "Complete"
        End If
    End Sub

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我已经使用了这种方法，并使其发挥作用

Protected Sub PageDetailsView_ItemCommand(sender As Object, e As DetailsViewCommandEventArgs)
    If Me.PageDetailsView.DefaultMode = DetailsViewMode.[ReadOnly] Then  
        If e.CommandName.Equals("GenerateModifiedDate", StringComparison.CurrentCultureIgnoreCase) Then 
            Dim modifiedDateLabel As Label = TryCast(Me.PageDetailsView.FindControl("ModifiedDateLabel"), Label)
            modifiedDateLabel.Text = DateTime.Now.ToString()
        End If 
    Else
        If e.CommandName.Equals("GenerateModifiedDate", StringComparison.CurrentCultureIgnoreCase) Then
           Dim modifiedDateTextbox As TextBox = TryCast(Me.PageDetailsView.FindControl("ModifiedDateTextbox"), TextBox)
           modifiedDateTextbox.Text = DateTime.Now.ToString()
        End If 
    End If
End Sub