using server variables in a href <%= xx %> with runat=server

Question

When I use an anchor tag on an aspx page as below,

<a href="~/pages/page.aspx?id=<%= ServervariableName %>"> test </a>

it will get the variable value correctly assigned to id but it won't route the page correctly as the ~ will not be evaluated without the runat="server" attribute on the 'a' tag. But once I add the runat server attribute, it does not evaluate the servervariable name anymore.. Does anyone know how this works or what I should do to take care of both?

Answer 1

Try the following:

href="<%= ResolveUrl("~/pages/page.aspx") + "?id=" + ServervariableName %>"

This will only work if you do not add runat="server".

Answer 2

You cannot use this syntax to set properties of server-side controls.

Instead, you can set the property in the code-behind, or use data-binding syntax (<%# expression %>) and call DataBind() in the code-behind.

Answer 3

If you want both runat=server and a virtual path you either of:

1. Set the href in your code behind. Afaik MapPath doesn't remove query strings.
2. If you don't want to use MapPath, you can use VirtualPathUtility which MapPath uses internally most likely.

3. If you want to bind the variable in your .aspx-file and still want runat="server", then you have to use an expression builder. You syntax then becomes

   <a href="~/folder/page.aspx?id=<%$ MyVars:ServerVariableName %>" runat="server">The link</a>

PM me if you need help with it. It's quite useful for customizing localization and for interfacing the ASP.Net compiler (i.e. not the C#/VB one, but the one that can compile ASPX-pages)