Cannot use Response.Write in section of aspx page?

Question

I'm trying to use the Response.Write() method to dynamically insert content in the < head > section of an aspx page. I need to inject a string value from a property on a code-behind object which is a link to my CSS file. However, it is not being processed properly at run time. The object is public on the class and is hydrated in the Page_Load() event. Down in the body of the page I can successfully inject other properties from the Corpoartion object with no problem at all.

Why does this not work in the < head > section?

This is the part that does not expand correctly:

<link href="<%= Corporation.PageStyleSheet %>" rel="stylesheet" type="text/css" />

Here is the entire < head > section:

<head runat="server">
    <title></title>
    <link href="<%= Corporation.PageStyleSheet %>" rel="stylesheet" type="text/css" />
    <script language="JavaScript" type="text/JavaScript" src="cntv_menu.js"></script>
    <script language="JavaScript" type="text/JavaScript" src="cntv_category.js"></script>   
</head>

What is the reason that this will not expand properly?

In case others stumble here, the accepted answer has a slight mistake: CAN be used inside a element, I use it all the time for comment, and <script> variables (only <link> and <meta> elements are known to be a problem). I only needed to give the <link> element an ID= property then set the href property in code-behind.</script> — JayRO-GreyBeard, Sep 28 '15 at 17:18

score 6 · Accepted Answer · edited May 23 '17 at 12:16

6

You can't use <%= %> inside a runat="server" tag, which your <head> tag is.

You can either change it to <%# %> and DataBind to it in the code-behind, or you can make the link tag runat="server", give it an id and assign the attribute from the code behind.

See this answer, which goes into the details.

edited May 23 '17 at 12:16

Community

1
1

answered Feb 18 '10 at 16:10

Richard Szalay

78,647
19
169
223

Thanks. You got me going. < head > had runat="server" already, so it turns out I did not need to add that to the link, but I did give the link an id="csslink" and then in codebehind, I call csslink.DataBind(). Works like a charm! – MattSlay Feb 18 '10 at 16:51
I realize that this is nearly a decade old, but I stumbled across it and felt it was worth noting that `` can't be used inside of a quoted identifier within a server control (e.g., within `
`). In those cases—as counter-intuitive as it seems if you're thinking of the declarative syntax as HTML elements—you must remove the attribute quotes. E.g., ` rel="stylesheet" type="text/css" />`. This will still render with quotes around the attribute value.
– Jeremy Caney Sep 30 '19 at 19:56

score 0 · Answer 2 · edited Feb 23 '17 at 15:15

0

Use this:

this.myButton.Attributes.Add(attribute, value);

It worked for me :)

edited Feb 23 '17 at 15:15

Nissa

4,589
8
27
37

answered Feb 23 '17 at 14:54

Cristian

21
3

score 0 · Answer 3 · answered Jun 06 '18 at 14:31

the best way to resolve this problem is using OnPreRender

Example:

First, define your tag:

<link href="~/css/your_default.css" type="text/css" runat="server" id="myCSS" />

And on the OnPreRender:

protected override void OnPreRender(EventArgs e){
     base.OnPreRender(e);
     myCSS.Attributes["href"] = "~/css/your_new.css";
}

score -1 · Answer 4 · answered Feb 18 '10 at 16:15

-1

If you write out the full line you should be ok:

<%
Response.write("<link href=\"" + Corporation.PageStyleSheet + "\" rel=\"stylesheet\" />");
%>

P.S. My syntax may not be completely right, sorry in advance.

answered Feb 18 '10 at 16:15

Luke Duddridge

4,123
31
50

That won't work for the same reason that `` doesn't work. The code within a runat=server control is parsed as a server-control tree only. – Richard Szalay Feb 18 '10 at 16:50
Good idea for thinking outside the box (kind of), but, as stated, it still doesn't work. Sorry, man. – MattSlay Feb 19 '10 at 00:23
That's odd, because I have it working in a head runat="server" Does ASP.NET runat Server work differently from MVC? or is it because my head section is inside a masterpage anyone know? – Luke Duddridge Feb 19 '10 at 08:24
FYI, you shouldn't be using head runat="server" with ASP.NET MVC as doing so mixes control hierarchies (webforms) with MVC – Richard Szalay Mar 01 '10 at 09:11

Cannot use Response.Write in section of aspx page?

4 Answers4