How to get controller name when Web API versioning with routing attributes

Question

I need to get the controller name from my route and this I can do if using standard routing code in WebApiConfig.

However, if I am using routing attributes it starts to get a little difficult, especially when trying to version.

Example: If I call an api/terms/bonuses and I have a BonusController and BonusV2Controller and a BonusV3Controller, this code returns the latest controller version 3. That's ok, I can live with that returning the latest and greatest version as a default.

var attributedRoutesData = request.GetRouteData().GetSubRoutes();
var subRouteData = attributedRoutesData.FirstOrDefault();

var actions = (ReflectedHttpActionDescriptor[])subRouteData.Route.DataTokens["actions"];
//This seems to get latest controller name. ie. V2
controllerName = actions[0].ControllerDescriptor.ControllerName;

Now if I request a version 1, for simplicity I'll use a querystring and call api/terms/bonuses?v=2

So this code no longer works (obviously).

How do I get the V2 controller name?

If I abandon routing attributes and just use WebApiConfig routing, this code works happily.

HttpControllerDescriptor controllerDescriptor = null; 
var controllers = GetControllerMapping();
var routeData = request.GetRouteData();
var controllerName = (string)routeData.Values["controller"];

UPDATE:

Here is my full selector code.

IDictionary<string, HttpControllerDescriptor> controllers = GetControllerMapping();                                             

var attributedRoutesData = request.GetRouteData().GetSubRoutes();
var subRouteData = attributedRoutesData.LastOrDefault(); //LastOrDefault() will get PeopleController, FirstOrDefault will get People{version}Controller which we don't want

var actions = (ReflectedHttpActionDescriptor[])subRouteData.Route.DataTokens["actions"];
var controllerName = actions[0].ControllerDescriptor.ControllerName;


//For controller name without attribute routing
//var controllerName = (string)routeData.Values["controller"];

HttpControllerDescriptor oldControllerDescriptor;
if (controllers.TryGetValue(controllerName, out oldControllerDescriptor))
{
    //TODO: Different techniques for handling version api requests.
    var apiVersion = GetVersionFromQueryString(request);
    //var version = GetVersionFromHeader(request);
    //var version = GetVersionFromAcceptHeaderVersion(request);
    //var version = GetVersionFromMediaType(request);

    if (!String.IsNullOrEmpty(apiVersion))
    {
        var newControllerName = String.Concat(controllerName, "V", apiVersion);

        HttpControllerDescriptor newControllerDescriptor;
        if (controllers.TryGetValue(newControllerName, out newControllerDescriptor))
        {
            return newControllerDescriptor;
            }
        }
        return oldControllerDescriptor;
    }
    return null;

Could you share your complete implementation of SelectController of your controller selector to get a good idea? — Kiran
– Kiran, Commented Jan 17, 2014 at 16:29
you can also take a look at the following post: stackoverflow.com/questions/19835015/… — Kiran
– Kiran, Commented Jan 17, 2014 at 16:35
With that UPDATE, I now get an error. {"$id":"1","message":"An error has occurred.","exceptionMessage":"The given key was not present in the dictionary.","exceptionType":"System.Collections.Generic.KeyNotFoundException","stackTrace":" at System.Collections.Generic.Dictionary2.get_Item(TKey key)\r\n at System.Web.Http.Controllers.ApiControllerActionSelector.ActionSelectorCacheItem.FindActionMatchRequiredRouteAndQueryParameters(IEnumerable1 candidatesFound)\r\n at ...... — richardb
– richardb, Commented Jan 17, 2014 at 16:55

Naveen K · Accepted Answer · 2014-06-17 00:07:02Z

2

 var subRouteData = request.GetRouteData().GetSubRoutes().LastOrDefault();

 if (subRouteData != null && subRouteData.Route != null)
 {
  var actions = subRouteData.Route.DataTokens["actions"] as HttpActionDescriptor[];

  if (actions != null && actions.Length > 0)
  {
     controllerName = actions[0].ControllerDescriptor.ControllerName;
  }
}

answered Jun 17, 2014 at 0:07

Naveen K

212 bronze badges

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1 Comment

bob Over a year ago

So, to get this straight. If I want the controller name, while inside the controller, I have to use:

((HttpActionDescriptor[]) Request.GetRouteData().GetSubRoutes().Last().Route.DataTokens["actions"])[0].ControllerDescriptor.ControllerName

At what point would this be appropriately classified as a rube goldberg system?

Oren Levy · Accepted Answer · 2021-05-19 19:14:04Z

0

At last I found it:

filterContext.ActionContext.ControllerContext.ControllerDescriptor.ControllerName

answered May 19, 2021 at 19:14

Oren Levy

113 bronze badges

1 Comment

Michael Z. Over a year ago

I would have liked to have seen more clarity on your answer but this does look like it could help someone. It's similar to another answer, but is more concise.

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