asp.net - Asp.net RenderControl 方法不为下拉列表呈现自动回发

Question

我有点困惑，为什么在使用 RenderControl 方法时，asp.net 不呈现 autopostback 属性设置为 true 的下拉列表。

例如

 Dim sw As New IO.StringWriter
    Dim tw As New HtmlTextWriter(sw)

    Dim table As New Table

    table.Rows.Add(New TableRow)
    Dim tr As TableRow = table.Rows(0)

    tr.Cells.Add(New TableCell)
    Dim tc As TableCell = tr.Cells(0)

    Dim ddlMyValues As New DropDownList
    ddlMyValues.ID = "ddl1"

    ddlMyValues.Items.Add("Test1")
    ddlMyValues.Items.Add("Test2")
    ddlMyValues.Items.Add("Test3")
    ddlMyValues.AutoPostBack = True

    tc.Controls.Add(ddlMyValues)
    table.RenderControl(tw)

    Debug.WriteLine(sw.ToString)

我的输出呈现的下拉列表没有 onchange="javascript:setTimeout('__doPostBack(\ddl1\',\'\')', 0)" 正常使用下拉列表时由 asp.net 生成的。

有解决办法吗？

Answer 1

Just a guess, but it might be because it's not inside a form element. Why would you want to do this anyway?