使用LoadControl以编程方式加载WebControl（而非UserControl）
[英]Use LoadControl to programmatically load WebControl (not UserControl)
问题描述
I have a custom WebControl class that represents a HyperLink surrounded by an li (list item) element. 
我有一个自定义WebControl类，该类表示一个由li （列表项）元素包围的HyperLink 。 I would like to be able to load this control and add it to the page programmatically. 我希望能够加载此控件并将其以编程方式添加到页面中。
Here is the custom web control ( ListItemHyperLink.cs ): 这是自定义Web控件（ ListItemHyperLink.cs ）：
public class ListItemHyperLink : HyperLink
{
public string ListItemCssClass { get; set; }
public override void RenderBeginTag(HtmlTextWriter writer)
{
if (!String.IsNullOrWhiteSpace(ListItemCssClass))
{
writer.AddAttribute(HtmlTextWriterAttribute.Class, ListItemCssClass);
}
writer.RenderBeginTag("li");
base.RenderBeginTag(writer);
}
public override void RenderEndTag(HtmlTextWriter writer)
{
base.RenderEndTag(writer);
writer.RenderEndTag();
}
}
Here is the page I am attempting to add it to ( Test.aspx ): 这是我尝试将其添加到（ Test.aspx ）的页面：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Test.aspx.cs" Inherits="Example.Test" %>
<!DOCTYPE html>
<html>
<head runat="server">
<title>My Page</title>
</head>
<body>
<form id="Form1" runat="server">
<ul runat="server" ID="UnorderedList">
</ul>
</form>
</body>
</html>
And here is my attempt to load the control dynamically in the code-behind of the page ( Test.aspx.cs ): 这是我尝试在页面代码（ Test.aspx.cs ）中动态加载控件：
public partial class Test : Page
{
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
var listItemHyperLink = (ListItemHyperLink) LoadControl("~/Controls/ListItemHyperLink.cs");
listItemHyperLink.Text = "Google";
listItemHyperLink.NavigateUrl = "http://google.com/";
listItemHyperLink.ListItemCssClass = "li-class";
listItemHyperLink.CssClass = "a-class";
UnorderedList.Controls.Add(listItemHyperLink);
}
}
When I try this, I get the following Exception: 尝试此操作时，出现以下异常：
Unable to cast object of type 'System.Web.Compilation.BuildResultCompiledAssembly' to type 'System.Web.Util.IWebObjectFactory'.
This exception is thrown on the line where I call LoadControl() . 我调用LoadControl()的行上引发了此异常。
How can I use LoadControl() (or some other method) to use this control from code? 如何使用LoadControl() （或其他方法）从代码中使用此控件？
2 个解决方案
解决方案1
2 已采纳 2013-07-25 20:01:06
Just enstantiate your custom control and add it to the Controls collection. 只需实例化自定义控件并将其添加到Controls集合中即可。 LoadControl is for UserControls. LoadControl用于UserControls。
var listItemHyperLink = new ListItemHyperLink();
listItemHyperLink.Text = "Google";
listItemHyperLink.NavigateUrl = "http://google.com/";
listItemHyperLink.ListItemCssClass = "li-class";
listItemHyperLink.CssClass = "a-class";
UnorderedList.Controls.Add(listItemHyperLink);
解决方案2
1 2013-07-25 20:06:19
ListItemHyperLink is a server control, so you cannot load it like User control. ListItemHyperLink是一个服务器控件，因此无法像用户控件一样加载它。
protected void Page_Load(object sender, EventArgs e)
{
var listItemHyperLink = new ListItemHyperLink();
listItemHyperLink.Text = "Google";
listItemHyperLink.NavigateUrl = "http://google.com/";
listItemHyperLink.ListItemCssClass = "li-class";
listItemHyperLink.CssClass = "a-class";
UnorderedList.Controls.Add(listItemHyperLink);
}
It is kind of odd to see PageLoad using override method. 看到使用重写方法的PageLoad有点奇怪。 It is not normal unless you have a reason behind it. 除非您有其背后的原因，否则这是不正常的。 It is like using Int32 instead of int. 就像使用Int32而不是int一样。 I'm just saying; 我只是说; I hope you don't mind. 我希望你不要介意。
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.