ASP CascadingDropDown 控件导致 IE 脚本超时

Question

在加载页面之前，我使用一个子例程将 DropDownList 控件链接在一起：

Private Sub CreateCascadingDropDown(ByVal category As String, ByRef parentDDL As DropDownList, ByRef targetDDL As DropDownList)
            Dim CDDL As New CascadingDropDown
            With CDDL
                .Category = category
                If Not parentDDL Is Nothing Then
                    parentDDL.Items.Clear()
                    .ParentControlID = parentDDL.ID
                End If
                targetDDL.Items.Clear()
                .TargetControlID = targetDDL.ID
                .PromptText = SharedWeb.GC_SELECTONE
                .PromptValue = "-1"
                .LoadingText = "Please wait..."
                .ServicePath = "/ajax/InvestmentProcess.asmx"
                .ServiceMethod = "GetTaxo"
            End With
            'Page.ClientScript.RegisterForEventValidation(CDDL.UniqueID)
            targetDDL.Parent.Controls.Add(CDDL)
        End Sub

当调用 Web 服务方法时，它会执行以下代码。根据类别，它从适配器获取适当的数据。

<WebMethod()> _
    Public Function GetTaxo(ByVal knownCategoryValues As String, ByVal category As String) As CascadingDropDownNameValue()
        Dim log As ILog = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType)
        log.Debug("GetSegmentTaxonomy(" + category + ") -> {" + knownCategoryValues + "}")
        Dim kv As StringDictionary = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues)
        Dim adapter As New SegmentTaxonomyTableAdapters.SEGMENT_ARCHITECTURE_TableAdapter
        Dim rows As DataRowCollection

        Select Case category
            Case InvestmentEdit.ST_SEG_ARCH
                rows = New SegmentTaxonomyTableAdapters.SEGMENT_ARCHITECTURE_TableAdapter().GetData().Rows
            Case InvestmentEdit.ST_LOB
                If kv.ContainsKey(InvestmentEdit.ST_SEG_ARCH) Then
                    log.Debug("found seg architecture - > " + kv(InvestmentEdit.ST_SEG_ARCH))
                    rows = New SegmentTaxonomyTableAdapters.LINE_OF_BUSINESSTableAdapter().GetData(kv(InvestmentEdit.ST_SEG_ARCH)).Rows
                End If
        End Select

        If Not rows Is Nothing Then
            Dim results As New List(Of CascadingDropDownNameValue)
            For Each row As DataRow In rows
                log.Debug("ROW >>>> " + row("lov_label").ToString() + " : " + row("lov_cd").ToString())
                results.Add(New CascadingDropDownNameValue(row("lov_label"), row("lov_cd")))
            Next
            Return results.ToArray
        End If
        Return Nothing
    End Function

我需要将大约 5 个下拉列表链接在一起。如果顶级下拉控件 (myDDL) 是唯一像这样链接的控件，则它可以正常加载：

CreateCascadingDropDown("MyCat",Nothing,myDDL)

但是当我链接第二个下拉控件时，Internet Explorer 会出现脚本超时。如果我继续允许脚本运行，它只会继续给我提示。如果选择停止运行脚本，我会收到方法错误 12031 或错误 500（是的，我的 Web 服务文件中有 ScriptService() 声明）。关于造成这种情况的原因有什么想法吗？

Answer 1

事实证明，我只需要从 Ajax Control Toolkit 添加以下控件：

<ajax:ToolkitScriptManager ID="tsm" runat="server" />

我需要使用：而不是 .TargetControlID = targetDDL.ID：

.TargetControlID = targetDDL.UniqueId