Question

I’m having some trouble getting routes to match.

I am using base-32 encoded int’s as short links to slideshows in a web app. There are 5 different versions of each slideshow, and I am using an initial letter to distinguish between each version.

The routes always match, except when the first character of the base-32 encoded int is the same as the character designating the slideshow version. This anomaly exists for all 5 prefix letters: n, f, c, x, and h.

What about the first two characters being the same makes these routes not match? I’m at a loss to understand what’s going on here (when the routes don’t match, they simply fall through to the default).

Route Matches (/na0):

Route Doesn’t Match (/nn0):

Route Matches (/nfg):

Route Doesn’t Match (/ffg):

I’m boggled. Here’s the routing code, in case it isn’t clear in the RouteDebug tables in the screenshots:

        routes.MapRoute(
            "NonBrandedSlideshow",
            "n{id}",
            MVC.Slideshow.NonBranded(), null,
            new { id = Settings.Base32Regex }
        );

        routes.MapRoute(
            "FullSlideshow",
            "f{id}",
            MVC.Slideshow.Full(), null,
            new { id = Settings.Base32Regex }
        );

        routes.MapRoute(
            "CompactSlideshow",
            "c{id}",
            MVC.Slideshow.Compact(), null,
            new { id = Settings.Base32Regex }
        );

        routes.MapRoute(
            "FlexibleSlideshow",
            "x{id}",
            MVC.Slideshow.Flexible(), null,
            new { id = Settings.Base32Regex }
        );

        routes.MapRoute(
            "Html5Slideshow",
            "h{id}",
            MVC.Slideshow.NonBrandedHtml5(), null,
            new { id = Settings.Base32Regex }
        );

I should note here that I am using T4MVC (see section 2.2.5), and these MapRoute methods are extensions added by T4MVC. The MapRoute methods I am using are equivalent to the standard methods, and I have tried using the non-T4MVC MapRoute method with the same result:

        routes.MapRoute(
            "Html5Slideshow",
            "h{id}",
            new { controller = "Slideshow", action = "NonBrandedHtml5" },
            new { id = Settings.Base32Regex }
        );

Here is the Base32Regex, though I have tried it with and without this constraint (the Base32 implementation I am using will assume I and O are 1 and 0, for example).

public static partial class Settings
{
    public static string Base32Regex
    {
        get { return @"[0-9ABCDEFGHJKMNPQRSTVWXYZ]+"; }
    }
}

Answer 1

Well, I am just as boggled. I performed some other tests and as far as I can see, this has to be some bug in the way the routes are checked when the constant before the route parameter has the same repeated character. Some other boggling examples:

"nn{id}"
route matches (/nna0)
route doesn't match (/nnn0)

"nnn{id}"
route matches (/nnna0)
route doesn't match (/nnnn0)

as soon as i make the constant not repeat the same character, all is well

"mn{id}"
route matches (/mna0)
route matches (/mnn0)
route matches (/mnmn)

This may not be exactly what you are looking for. But given the oddity of the situation, it was the only thing I could come up with. Add the constant to the constraint and remove it from the url. Then in your controller (this is the part I didn’t like) you will need to remove that constant from the id parameter. Hope this works, or at the least help spark another solution.

routes.MapRoute(
    "NonBrandedSlideshow",
    "{id}",
    MVC.Slideshow.NonBranded(), null,
    new { id = "n"+Settings.Base32Regex }
);

UPDATE:

I guess this is a known issue, thanks @max-toro