如何在代码后面隐藏html LI控件?

Question

我试图隐藏<li>，但它不工作:

<li runat="server" id="theLi">This is test</li>

c#代码:

theLi.Visible = false;

错误* *

System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.

Answer 1

参考:如何:按ID访问服务器控件https://learn.microsoft.com/en-us/previous-versions/y81z8326 (v = vs.140) ? redirectedfrom = MSDN

您可能正在尝试访问命名容器内的控件。

private Control FindControlRecursive(Control rootControl, string controlID)
{
if (rootControl.ID == controlID) return rootControl;
foreach (Control controlToSearch in rootControl.Controls)
{
Control controlToReturn = 
FindControlRecursive(controlToSearch, controlID);
if (controlToReturn != null) return controlToReturn;
}
return null;
}

一旦你调用了这个函数，你可以使用可见性状态

var ctrl = FindControlRecursive(this, "theLi");
if (ctrl !=null) {
ctrl.Visible = false;
}