通过嵌套的 ajax 手风琴 Web 控件向上遍历；类型检查和 FindControl

Question

我有嵌套的 ajax 手风琴 Web 控件（嵌套 3 层或有时 4 层），我正在尝试找到嵌套的手风琴的父手风琴。我想在最深层的手风琴中的任何一个成为数据绑定时执行此操作。

protected void grandChildAccordion_ItemDataBound(object sender, AjaxControlToolkit.AccordionItemEventArgs e)
{
    if (e.AccordionItem.ItemType == AjaxControlToolkit.AccordionItemType.Header)
    {
         // find parent accordion
    }
}

有时，父折叠面板将处于 e.AccordionItem.Parent.Parent.Parent 级别或 e.AccordionItem.Parent.Parent.Parent.Parent 级别。

那么，如何检查 e.AccordionItem.Parent 是否等于 AjaxControlToolkit.AccordionContentPanel “type”？

（不太优雅）解决方案：我有嵌套的手风琴，最深的手风琴级别包含文档列表，每个手风琴标题都有一个显示计数的标签嵌套在其中的文档。从最深的手风琴级别开始，我获得文档计数，我遍历嵌套的手风琴并找到每个手风琴标题，使我能够找到他们的文档计数标签并为其添加一个值..希望这对某人有帮助：

// Save doc count. It will be displayed in doc count label within current accordion header, and the value will then be added to the doc count of each parent accordion's header.
int curDocCount = qcDocsBO.FetchQCDocumentCountByProjectID(SessionHandler.ProjectID, qcDocsBO.LSDItemID);
lblDocCount.Text = curDocCount.ToString();

// A deep-most accordion has just been DataBound. Start traversing upwards through nested accordions, adding the doc count to each parent accordion header's doc count label.
AjaxControlToolkit.Accordion curAccordion = sender as AjaxControlToolkit.Accordion;
AjaxControlToolkit.AccordionPane parentAccCP = curAccordion.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;
if (parentAccCP == null)
    parentAccCP = curAccordion.Parent.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;
while (parentAccCP != null)
{
    Label parentDocCountLabel = (Label)parentAccCP.FindControl("lblDocCount");
    if (parentDocCountLabel.Text == "")
        parentDocCountLabel.Text = "0";
    parentDocCountLabel.Text = (Convert.ToInt32(parentDocCountLabel.Text) + curDocCount).ToString();

    AjaxControlToolkit.AccordionPane nextParentAccCP = parentAccCP.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;

    if (nextParentAccCP == null)
        nextParentAccCP = parentAccCP.Parent.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;
    if (nextParentAccCP == null)
        nextParentAccCP = parentAccCP.Parent.Parent.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;
    if (nextParentAccCP == null)
        nextParentAccCP = parentAccCP.Parent.Parent.Parent.Parent.Parent.Parent as AjaxControlToolkit.AccordionPane;
    if (nextParentAccCP != null)
        parentAccCP = nextParentAccCP;
    else
        parentAccCP = null;
}

Answer 1

您始终可以使用 is 关键字进行类型检查，或使用 as 关键字进行安全转换。

请考虑以下情况：

if(e.AccordionItem.Parent is AjaxControlToolkit.AccordionContentPanel) {
   ...
}

则此

var accordion = e.AccordionItem.Parent as AjaxControlToolkit.AccordionContentPanel;
if(accordion != null) {
   ...
}

如果安全转换不成功，

accordion 为 null。使用这两种技术中的一种或两种，您可以在层次结构中向上迭代，并在遇到要查找的类型时停止。