如何在 .NET (C#) 中获取 UserControl 的 HTML 输出？
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How do I get the HTML output of a UserControl in .NET (C#)?
提问by Jon Smock
If I create a UserControl and add some objects to it, how can I grab the HTML it would render?
如果我创建一个 UserControl 并向其添加一些对象，我如何获取它会呈现的 HTML？
ex.
前任。
UserControl myControl = new UserControl();
myControl.Controls.Add(new TextBox());
// ...something happens
return strHTMLofControl;
I'd like to just convert a newly built UserControl to a string of HTML.
我只想将新建的 UserControl 转换为 HTML 字符串。
采纳答案by azamsharp
You can render the control using Control.RenderControl(HtmlTextWriter).
您可以使用Control.RenderControl(HtmlTextWriter).
Feed StringWriterto the HtmlTextWriter.
饲料StringWriter的HtmlTextWriter。
Feed StringBuilderto the StringWriter.
饲料StringBuilder的StringWriter。
Your generated string will be inside the StringBuilderobject.
您生成的字符串将在StringBuilder对象内。
Here's a code example for this solution:
这是此解决方案的代码示例：
string html = String.Empty;
using (TextWriter myTextWriter = new StringWriter(new StringBuilder()))
using (HtmlTextWriter myWriter = new HtmlTextWriter(myTextWriter))
{
myControl.RenderControl(myWriter);
html = myTextWriter.ToString();
}
回答by Joel Coehoorn
Call it's .RenderControl()method.
调用它的.RenderControl()方法。
回答by Xian
override the REnderControl method
覆盖 REnderControl 方法
protected override void Render(HtmlTextWriter output)
{
output.Write("<br>Message from Control : " + Message);
output.Write("Showing Custom controls created in reverse" +
"order");
// Render Controls.
RenderChildren(output);
}
This will give you access to the writer which the HTML will be written to.
这将使您可以访问将写入 HTML 的编写器。
You may also want to look into the adaptive control architecture of asp.net adaptive control architecture of asp.netwhere you can 'shape' the default html output from controls.
您可能还想查看 asp.net 自适应控制架构的自适应控制架构，您可以在其中“塑造”控件的默认 html 输出。
回答by Ben Aston
//render control to string
StringBuilder b = new StringBuilder();
HtmlTextWriter h = new HtmlTextWriter(new StringWriter(b));
this.LoadControl("~/path_to_control.ascx").RenderControl(h);
string controlAsString = b.ToString();
回答by theJerm
UserControl uc = new UserControl();
MyCustomUserControl mu = (MyCustomUserControl)uc.LoadControl("~/Controls/MyCustomUserControl.ascx");
TextWriter tw = new StringWriter();
HtmlTextWriter hw = new HtmlTextWriter(tw);
mu.RenderControl(hw);
return tw.ToString();
回答by Reikim
Seven years late, but this deserves to be shared.
晚了七年，但这值得分享。
The generally accepted solution - StringBuilderinto StringWriterinto HtmlWriterinto RenderControl- is good. But there are some gotchas, which I unfortunately ran across while trying to do the same thing. Some controls will throw errors if they're not inside of a Page, and some will throw errors if they're not inside of a <form>with runat="server". The ScriptManager control exhibits both of these behaviours.
普遍接受的解决方案 - StringBuilderinto StringWriterinto HtmlWriterinto RenderControl- 很好。但是有一些问题，不幸的是我在尝试做同样的事情时遇到了这些问题。如果某些控件不在 a 之内Page，则会抛出错误，而有些控件如果不在<form>with 之内，则会抛出错误runat="server"。ScriptManager 控件表现出这两种行为。
I eventually found a workaround here.The gist of it is basically just instantiating a new Page and Form before doing the writer work:
我最终在这里找到了解决方法。它的要点基本上只是在做作者工作之前实例化一个新的页面和表单：
Page page = new Page();
page.EnableEventValidation = false;
HtmlForm form = new HtmlForm();
form.Name = "form1";
page.Controls.Add(form1);
MyControl mc = new MyControl();
form.Controls.Add(mc);
StringBuilder sb = new StringBuilder();
StringWriter sw = new StringWriter(sb);
HtmlTextWriter writer = new HtmlTextWriter(sw);
page.RenderControl(writer);
return sb.ToString();
Unfortunately, this gives you more markup than you actually need (since it includes the dummy form). And the ScriptManager will still fail for some arcane reason I haven't puzzled out yet. Honestly, it's a whole lot of trouble and not worth doing; the whole point of generating controls in the code-behind is so that you don't have to fiddle around with the markup, after all.
不幸的是，这为您提供了比实际需要更多的标记（因为它包含虚拟表单）。而且 ScriptManager 仍然会因为一些我还没有弄清楚的神秘原因而失败。老实说，这很麻烦，不值得做；毕竟，在代码隐藏中生成控件的全部意义在于，您不必摆弄标记。
回答by Carl in 't Veld
You could utilize the HttpServerUtility.ExecuteMethod, available through HttpContext.Current.Server.Execute:
您可以使用该HttpServerUtility.Execute方法，可通过HttpContext.Current.Server.Execute以下方式获得：
var page = new Page();
var myControl = (MyControl)page.LoadControl("mycontrol.ascx");
myControl.SetSomeProperty = true;
page.Controls.Add(myControl);
var sw = new StringWriter();
HttpContext.Current.Server.Execute(page, sw, preserveForm: false);
The benefit would be that you also trigger the Page_Load event of your user control.
好处是您还可以触发用户控件的 Page_Load 事件。
MSDN documentation can be found here: https://msdn.microsoft.com/en-us/library/fb04e8f7(v=vs.110).aspx.
MSDN 文档可以在这里找到：https: //msdn.microsoft.com/en-us/library/fb04e8f7(v=vs.110).aspx。
