在 C# 中以编程方式添加元标记
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Adding meta tag programmatically in C#
提问by subha
I'm trying to programmatically add a <meta>. It is working fine when there is a Headelement with runat = "server"in the .aspxpage.
我正在尝试以编程方式添加一个<meta>. 它工作正常时，有一个Head元素与runat = "server"在.aspx页。
The code behind is:
后面的代码是：
HtmlMeta meta = new HtmlMeta();
meta.Name = "robots";
meta.Content = "noindex,follow";
this.Page.Header.Controls.Add(meta);
But I have some script in the head tag which contains code blocks like <% ... %>, so I cannot keep the runat = "server"value.
但是我在 head 标签中有一些脚本，其中包含像 一样的代码块<% ... %>，所以我无法保留该runat = "server"值。
The problem is I have to add the meta tag programmatically, because it depends on a value from the database.
问题是我必须以编程方式添加元标记，因为它取决于数据库中的值。
Is there a way to solve this issue so that my script inside the head element works as usual and I can add a meta tag programmatically?
有没有办法解决这个问题，以便我在 head 元素内的脚本照常工作，并且我可以以编程方式添加元标记？
采纳答案by awe
OK, I tested the answer by veggerby, and it works perfectly:
In the <header>section:
在该<header>部分：
<asp:PlaceHolder id="MetaPlaceHolder" runat="server" />
Note that Visual Studio might show a warning on the PlaceHolder tag, because it is not recognised as a known element inside the header, but you can ignore this. It works.
请注意，Visual Studio 可能会在 PlaceHolder 标记上显示警告，因为它未被识别为标头内的已知元素，但您可以忽略这一点。有用。
In the C# code:
在 C# 代码中：
HtmlMeta meta = new HtmlMeta();
meta.Name = "robots";
meta.Content = "noindex,follow";
MetaPlaceHolder.Controls.Add(meta);
Alternatively (since you already have code blocks using <% %>in your header section), you can tag the meta directly and retrieve only the value from server side:
或者（因为您已经<% %>在标题部分使用了代码块），您可以直接标记元并仅从服务器端检索值：
<meta name="robots" content="<%=GetMetaRobotsValueFromDatabase()%>" />
回答by Mike
Try moving whatever it is that you are doing in the <% .... %> to the code-behind. If you are using the script to add content into the page, you can replace it with an asp:Literal control and then set the value you were previously calculating in the script block to the code-behind and set Literal.Text to that value.
尝试将您在 <% .... %> 中所做的任何事情移到代码隐藏中。如果您使用脚本向页面添加内容，您可以将其替换为 asp:Literal 控件，然后将您之前在脚本块中计算的值设置为代码隐藏，并将 Literal.Text 设置为该值。
回答by veggerby
I haven't tested it, but maybe you can add an <asp:Placeholder>inside the <head></head>tag and add the meta tags to this.
我还没有测试过，但也许您可以<asp:Placeholder>在<head></head>标签内添加一个并将元标签添加到其中。
回答by Timothy Khouri
Or you could just put your meta-tag in the header, with an ID and a runat="server"... then in the code behind say
或者你可以把你的元标记放在标题中，带有一个 ID 和一个 runat="server"...然后在后面的代码中说
myMetaTag.Content = "noindex,follow";
or
或者
myMetaTag.Visible = false;
or whatever you'd like.
或者任何你想要的。
回答by Jonathan Williams
Many thanks to Awe for the solution! I have implemented this code in a (error404.ascx) ASP.NET User Control as follows:
非常感谢Awe 的解决方案！我已经在 (error404.ascx) ASP.NET 用户控件中实现了这段代码，如下所示：
<%@ Control Language="C#"%>
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
Response.TrySkipIisCustomErrors = true; //Suppress IIS7 custom errors
Response.StatusCode = 404;
SetRobotsHeaderMetadata();
}
private void SetRobotsHeaderMetadata()
{
HtmlMeta meta = new HtmlMeta();
meta.Name = "robots";
meta.Content = "noindex,follow";
this.Page.Master.FindControl("cphPageMetaData").Controls.Add(meta);
}
</script>
With the following masterpage:
使用以下母版页：
<%@ Master Language="C#" AutoEventWireup="true" Inherits="MyMaster" %>
<script runat="server">
...
</script>
<!DOCTYPE html>
<html lang="en-GB">
<head>
<title>Site title here</title>
<asp:contentplaceholder runat="server" id="cphPageMetaData">
</asp:contentplaceholder>
</head>
<body>
...
</body>
</html>
回答by hemantrautela
The best solution for this, which I successfully checked without any error or warning:
对此的最佳解决方案，我已成功检查，没有任何错误或警告：
The JavaScript code, which contains the <% ... %>code, was removed from the headsection and placed in the bodysection.
包含<% ... %>代码的 JavaScript 代码已从该head部分中删除并放置在该body部分中。
回答by George Filippakos
You could define your meta tag as a static string like so:
您可以将元标记定义为静态字符串，如下所示：
Private Shared MetaLanguage As String =
String.Format("<meta http-equiv=""Content-Language"" content=""{0}""/>", CultureInfo.CurrentUICulture.TwoLetterISOLanguageName)
Then place them in your head like so:
然后像这样把它们放在你的头上：
<head runat="server">
<%=MetaLanguage%>
</head>
This allow you to use any meta tag values and is easy to read and customize. Note: The use of the Sharedkeyword (static) helps improve performance.
这允许您使用任何元标记值，并且易于阅读和自定义。注意：使用Shared关键字 (static) 有助于提高性能。
回答by Nathan
MetaDescription = "Your meta description goes here"; MetaKeywords = "Keyword1,Keyword2,Keyword3";
MetaDescription = "你的元描述在这里"; MetaKeywords = "Keyword1,Keyword2,Keyword3";
回答by SmartDev
I think this is the best approach:
我认为这是最好的方法：
this.Page.Header.Controls.Add(new LiteralControl(@"<meta ... />"));
Enjoy!
享受！
回答by user3425953
OK... I actually only use C#... Or HTML into C#. I never use codebehind, designer or webcontrols in the file aspx...So I program everythingfrom classes... And dynamically.
好吧...我实际上只使用 C#...或 HTML 转换为 C#。我从不在文件 aspx 中使用代码隐藏、设计器或 web 控件……所以我从类中编写所有内容……并且是动态的。
Result:
结果：
HtmlMeta meta = new HtmlMeta();
meta.Name = "robots";
`meta.Content = "Here is what you want";`
var page=HttpContext.Current.Handler as Page;
page.Header.Controls.Add(meta);
