How to enable use of both named and unnamed url parameters in Asp.Net MVC

Question

Most likely a very basic question, but still: In an ASP.Net MVC application, how can I enable a controller to respond to URLs that have either named or unnamed URL parameters.

With the following controller:

[Route("test/display/{scaleid}")]
public ActionResult Display(int scaleid)
{
    return View();
}

I try two URL requests - the first one works, the second one (where I specify the parameter name), doesn't work. Why is this?

http://localhost:43524/Test/Display/11
http://localhost:43524/Test/Display/?scaleid=11

Configure Routes in Route COnfig file stackoverflow.com/questions/2246481/… — Sreejith
– Sreejith, Commented Jun 29, 2015 at 6:47

Tieson T. · Accepted Answer · 2015-06-29 06:48:29Z

2

The last slash in

localhost:43524/Test/Display/?scaleid=11

will break the routing for that URL. This should resolve:

localhost:43524/Test/Display?scaleid=11

answered Jun 29, 2015 at 6:48

Tieson T.

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1 Comment

Proposition Joe Over a year ago

Unfortunately, I still get an error when taking out the last slash and trying the suggested URL. "Resource not found" for "/Test/Display"

dani herrera · Accepted Answer · 2015-06-29 06:53:09Z

1

1) Make parameter optional:

[Route("test/display/{scaleid:int?}")]
public ActionResult Display(int scaleid? = Nothing)
{
    return View();
}

2) If url parameter is missing, try to take it from query string:

   string scaleid_par = this.Request.QueryString["scaleid"];
   if (!scaleid.HasValue && !string.IsNullOrEmpty(scaleid_par) ) {
        int.TryParse( scaleid_par, scaleid );
   }

answered Jun 29, 2015 at 6:53

dani herrera

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2 Comments

Proposition Joe Over a year ago

Thanks - when I add "{scaleid:int?}" to the route, then it works. Why is this? Why can I use a named parameter in the URL when I introduce a type constraint on the route, and make it optional?

dani herrera Over a year ago

Not type needed to fix your code, just set it as optional/nullable (? char). Glad to help.

DavidVollmers · Accepted Answer · 2015-06-29 06:49:20Z

1

Because you told ASP, that the URL mapping is "test/display/scaleid". So in your second test "scaleid" is not defined.

I can not test it at the moment but please try this mapping: "test/display/{scaleid}?{scaleid}

answered Jun 29, 2015 at 6:49

DavidVollmers

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