SPUrl for WSS 3.0 or SharePoint Foundation

No, expression like <% $SPUrl:~sitecollection/Style Library/mystyles.css %> doesn't work for WSS or SharePoint Foundation. This is part of Publishing Infrastructure and you have to buy MOSS or SharePoint Server license to get it.

So, let's create our own ExpressionBuilder. I didn't implement 'language' support - obviously I need just Site and SiteCollection.


...
using System.Web.Compilation;
using Microsoft.SharePoint;

...
public class WSSUrlExpressionBuilder : ExpressionBuilder
{
public override CodeExpression GetCodeExpression
(System.Web.UI.BoundPropertyEntry entry, object parsedData, ExpressionBuilderContext context)
{
CodeTypeReferenceExpression thisType = new CodeTypeReferenceExpression(base.GetType());

CodePrimitiveExpression expression = new CodePrimitiveExpression(entry.Expression.Trim().ToString());

string evaluationMethod = "GetKeyValue";

return new CodeMethodInvokeExpression(thisType, evaluationMethod, new CodeExpression[] { expression });
}

public static object GetKeyValue(string expression)
{
SPWeb web = SPContext.Current.Web;

string key = "~SiteCollection";
if (expression.IndexOf(key, StringComparison.InvariantCultureIgnoreCase) == 0)
return web.Site.Url+expression.Substring(key.Length);

key = "~Site";
if (expression.IndexOf(key, StringComparison.InvariantCultureIgnoreCase) == 0)
return web.Url+ expression.Substring(key.Length);

return expression;
}

}
...


You need to put this class to some assembly and register it with your prefix(e.g. WSSUrl) in Web.Config


<configuration>
<system.web>
<compilation>
<expressionBuilders>
<add expressionPrefix="WSSUrl"
type="{your Namespace}.WSSUrlExpressionBuilder,{Assembly Name}"/>
</expressionBuilders>
</compilation>
</system.web>
</configuration>


Assembly Name should be fully qualified if you put the assembly into GAC.