RazorEngine WebApiTemplateBase @Url.Content()

Question

How can I get @Url.Content() working in my _Layout.cshtml when RazorEngine is being used from ASP.NET Web API?

RazorEngine (v.3.7.2) only deals with the Razor syntax and not the additional helper methods like @Html or @Url. These can be added by extending the TemplateBase<> and setting it in the configuration.

There are code examples in some old issues: #26, #29; in an unreleased, incomplete piece of code in MvcTemplateBase.cs; and in the documentation for Extending the Template Syntax.

My problem is I'm using ASP.NET Web API (v.1) which won't have HttpContext.Current (nor should it). I want to provide a UrlHelper as I want to use its Content() method but it needs to be instantiated with the HttpRequestMessage which won't be available.

Perhaps there's no way to get @Url helper methods for my compiled layout. Perhaps I need some other way of getting the absolute path from the virtual path. It seems I'd still need some way of checking the Request though.

Answer 1

A way to get this working is to follow the direction set by Extending the Template Syntax and use VirtualPathUtility.ToAbsolute() in a helper method.

using System.Web;
using RazorEngine.Templating;

namespace MyNamespace.Web
{
    public abstract class WebApiTemplateBase<T> : TemplateBase<T>
    {
        protected WebApiTemplateBase()
        {
            Url = new UrlHelper();
        }

        public UrlHelper Url;
    }

    public class UrlHelper
    {
        public string Content(string content)
        {
            return VirtualPathUtility.ToAbsolute(content);
        }
    }
}

Set up the TemplateService configuration with this extension of the TemplateBase<>.

var config =
    new RazorEngine.Configuration.TemplateServiceConfiguration
    {
        TemplateManager = new TemplateManager(),
        BaseTemplateType = typeof(WebApiTemplateBase<>)
    };