Question

I’m using Phil Haack’s URL routing for WebForms and I would like to define a route that’s “dynamic.” Let’s say I have this route:

“{any}.aspx” — goes to –> “~/PageProcessor.aspx”

This would take any request that’s not a physical page to the PageProcessor page. This works great. The problem is that, based on some data that comes from a database, I need certain pages to be routed to a different processor, let’s say DifferentPageProcessor.aspx. I can’t define a new route that catches all the .aspx files because the first one catches everything.

So, I would need a way to process the request before the “router” decides to take it to PageProcessor and fork it to either PageProcessor or DifferentPageProcessor as needed. Is this possible?

Thanks.

Answer 1

My solution — unless somebody comes up with a more elegant one — was to modify the WebFormRouteHandler class in the WebFormRouting project to accept a custom predicate.

public WebFormRouteHandler(string virtualPath, bool checkPhysicalUrlAccess, Func<RequestContext, string> custom)

Then inside the class I would store the custom parameter into private CustomVirtualPath property. To use it, I had to change GetSubstitutedVirtualPath to this:

public string GetSubstitutedVirtualPath(RequestContext requestContext)
{
  string path = VirtualPath;

  if (CustomVirtualPath != null)
  {
    path = CustomVirtualPath(requestContext);
  }

  if (!path.Contains("{")) return path;

  //Trim off ~/
  string virtualPath = path.Substring(2);

  Route route = new Route(virtualPath, this);
  VirtualPathData vpd = route.GetVirtualPath(requestContext, requestContext.RouteData.Values);
  if (vpd == null) return path;
  return "~/" + vpd.VirtualPath;
}

For the project to compile we need to change WebFormRoute and WebFormRouteExtensions to allow the passing of the custom parameter down the chain. When all done I can write this in global.asax.cs

routes.MapWebFormRoute("All", "{any}.aspx", "~/", false,
                         context =>
                           {
                             return ((string)context.RouteData.Values["any"] == "test"
                                       ? "~/PageProcessor.aspx"
                                       : "~/DifferentPageProcessor.aspx");
                           });

Of course the body of the lambda expression should look up the URL from some other place (database or cache).