Fixes: U4-5291 UmbracoVirtualNodeRouteHandler throws exception: parameter culture cannot be null and publicizes some routing extensions.

src/Umbraco.Web/Mvc/UmbracoVirtualNodeByIdRouteHandler.cs

@@ -3,11 +3,11 @@ using Umbraco.Core.Models;
 
 namespace Umbraco.Web.Mvc
 {
-    public abstract class UmbracoVirtualNodeByIdRouteHandler : UmbracoVirtualNodeRouteHandler
+    public class UmbracoVirtualNodeByIdRouteHandler : UmbracoVirtualNodeRouteHandler
     {
         private readonly int _realNodeId;
 
-        protected UmbracoVirtualNodeByIdRouteHandler(int realNodeId)
+        public UmbracoVirtualNodeByIdRouteHandler(int realNodeId)
         {
             _realNodeId = realNodeId;
         }
@@ -20,6 +20,9 @@ namespace Umbraco.Web.Mvc
             return FindContent(requestContext, umbracoContext, byId);
         }
 
-        protected abstract IPublishedContent FindContent(RequestContext requestContext, UmbracoContext umbracoContext, IPublishedContent baseContent);
+        protected virtual IPublishedContent FindContent(RequestContext requestContext, UmbracoContext umbracoContext, IPublishedContent baseContent)
+        {
+            return baseContent;
+        }
     }
 }

src/Umbraco.Web/Mvc/UmbracoVirtualNodeRouteHandler.cs

@@ -1,4 +1,6 @@
-using System.Web;
+using System.Globalization;
+using System.Linq;
+using System.Web;
 using System.Web.Mvc;
 using System.Web.Routing;
 using Umbraco.Core.Models;
@@ -42,6 +44,13 @@ namespace Umbraco.Web.Mvc
 
         protected virtual void PreparePublishedContentRequest(PublishedContentRequest publishedContentRequest)
         {
+            //need to set the culture for this to work
+            if (publishedContentRequest.Culture == null)
+            {
+                //none specified so get the default
+                var defaultLanguage = global::umbraco.cms.businesslogic.language.Language.GetAllAsList().FirstOrDefault();
+                publishedContentRequest.Culture = defaultLanguage == null ? CultureInfo.CurrentUICulture : new CultureInfo(defaultLanguage.CultureAlias);
+            }
         }
     }
 }

src/Umbraco.Web/RouteCollectionExtensions.cs

@@ -4,11 +4,30 @@ using System.Linq;
 using System.Web.Mvc;
 using System.Web.Routing;
 using System.Web.Http;
+using Umbraco.Web.Mvc;
 
 namespace Umbraco.Web
 {
-    internal static class RouteCollectionExtensions
+    public static class RouteCollectionExtensions
 	{
+        /// <summary>
+        /// Maps an Umbraco route with an UmbracoVirtualNodeRouteHandler
+        /// </summary>
+        /// <param name="routes"></param>
+        /// <param name="name"></param>
+        /// <param name="url"></param>
+        /// <param name="defaults"></param>
+        /// <param name="virtualNodeHandler"></param>
+        /// <param name="constraints"></param>
+        /// <param name="namespaces"></param>
+        /// <returns></returns>
+        public static Route MapUmbracoRoute(this RouteCollection routes, string name, string url, object defaults, UmbracoVirtualNodeRouteHandler virtualNodeHandler, object constraints = null, string[] namespaces = null)
+        {
+            var route = routes.MapRoute(name, url, defaults, constraints, namespaces);
+            route.RouteHandler = virtualNodeHandler;
+            return route;
+        }
+
         /// <summary>
         /// Routes a webapi controller with namespaces
         /// </summary>