.Net MVC routing producing a circular route

Question

I have a website that we have recently made some changes to, and this seems to have broken some of my routing.

the initial issue was that I was getting a 405 verb not allowed when using the following form.

using (@Html.BeginForm("Index", "Recommendations", FormMethod.Post))
{
  <button class="btn btn-large btn-primary"  d="btnNext">@ViewBag.TextDisplay</button>        
}

this was constructing a URL such that it was seen in the html as Recommendations/ , leaving Index out (presumably because it was a default parameter. However the index method signature was changed, so it took an optional parameter, which appeared to be causing the issue.

   [HttpPost]
    public async Task<ActionResult> Index(int? enquiryId)

To fix this, I added the following to my route.config file

    routes.MapRoute(
          name: "DefaultWithIndex",
          url: "Recommendations/{enquiryId}",
          defaults: new { controller = "Recommendations", action = "Index", enquiryId= UrlParameter.Optional });

        routes.MapRoute(
          name: "Default",
          url: "{controller}/{action}/{id}",
          defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
      );

But this has now had the side effect of intercepting any calls to other methods within the RecommendationsController, and redirecting me back to the index page ie Recommendations/index

So how do I change my routing config, so that

recommendations/ and recommendations/enquiryId=1 map to recommendations/index but Recommendations/<other method> goes to Recommendations/<other method> ?

Answer 1

Is enquiryId an int I assume? If so, you can constrain your route to only look for integers.

routes.MapRoute(
      name: "DefaultWithIndex",
      url: "Recommendations/{enquiryId}",
      defaults: new { controller = "Recommendations", action = "Index", enquiryId= UrlParameter.Optional },
      constraints: new {enquiryId= @"\d+" }); //restrict enquiryId to one or more integers

this will match /Recommendations/123 but not /Recommendations/MyCustomAction

Routes are greedy by default and will try to match all possible values before falling through to the next one.