ASP.NET MVC 5 routing optional parameters

Question

I've an Action in my ApiController that I want to invoke from a specific link, so I created this simple route

[Route("Rest/GetName/{name}")]
public IHttpActionResult GetName(string name) {
    // cut - code here is trivial but long, I just fill in an object to return as Json code
    return Json(myObject);
}

It works fine but I want to make the parameter optional. According to documentation adding a question point at the end of the parameter name in the route should be enough

[Route("Rest/GetName/{name?}")]

This way I get an error if I don't provide the optional parameter, so

.../Rest/GetName/AnyName --> ok
.../Rest/GetName/ --> error (see below)

{"Message":"No HTTP resource was found that matches the request URI 'https://localhost/miApp/Rest/GetName'.","MessageDetail":"No action was found on the controller 'Rest' that matches the request."}

Vadim Martynov · Accepted Answer · 2015-12-14 11:15:36Z

19

Web API requires to explicitly set optional values even for nullable types and classes.

Use default value to optional parameter:

[Route("Rest/GetName/{name?}")]
public IHttpActionResult GetName(string name = null) {
    // cut - code here is trivial but long, I just fill in an object to return as Json code
    return Json(myObject);
}

And don't forget about routing registration:

httpConfig.MapHttpAttributeRoutes()

edited Dec 14, 2015 at 11:15

answered Dec 14, 2015 at 11:01

Vadim Martynov

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Comments

Nauman Khan · Accepted Answer · 2015-12-14 12:48:44Z

There are many possible solutions:

Try Optional Parameter

   [Route("Rest/GetName/{name?}")]
   public IHttpActionResult GetName(string name = null) {
       // cut - code here        is trivial but long, I just fill in an               
       obj ect to return as 
       `enter code here`Json code
       return Json(myObject);
         }

2.Set PreFix on controller first

    [RoutePrefix("api/Rest")]
    [Authorize]
    public class RestController : ApiController
    {
         [Route("/GetName/{name}")]
         public IHttpActionResult GetName(string name = null) 
         {
         // cut - code here is trivial but long, I just fill in an object
         to  return as Json code
         return Json(myObject);
         }
     }

3.Write parameter before action name in route

   [RoutePrefix("api/Rest")]
    [Authorize]
    public class RestController : ApiController
    {
         [Route("{name}/GetName")]
         public IHttpActionResult GetName(string name = null) 
         {
         // cut - code here is trivial but long, I just fill in an object
         to  return as Json code
         return Json(myObject);
         }
     }

Hopefully this will help you to resolve your problem.Thanks

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