Routing with optional parameter in web-api

Question

Using web-api i go to /api/cat/orders/

I specified the following routes and controller methods. I expected that the "ApiRouteWithCategoryAndExtId" route and the "GetMessageByCategoryExtId" method would be used since I made "extid" optional. But it is using the default Get method.

(/api/cat/orders/id18 uses GetMessageByCategoryExtId, but then extid is not optional)

What am I doing wrong?

Routes:

config.Routes.MapHttpRoute(
    name: "ApiRouteUniqueId",
    routeTemplate: "api/def/{id}",
    defaults: new { id = RouteParameter.Optional, controller = "Default" }
);

config.Routes.MapHttpRoute(
    name: "ApiRouteWithCategoryAndExtId",
    routeTemplate: "api/cat/{category}/{extid}",
    defaults: new { extid = RouteParameter.Optional, controller = "Default"}
);

Controller:

public string Get()

public HttpResponseMessage GetMessageById(int id)

public HttpResponseMessage GetMessageByCategoryExtId(
    string category, string extid)

What is the default route, and is it defined before or after these other routes? — Brian Rogers
– Brian Rogers, Commented Mar 8, 2013 at 3:58
These are the only two routes, so I suppose the first is the default? It might have something to do with te web-api conventions, or just the fact that it matches the first route based on pattern, not on actual content. But I don't know how I check what is happening here. — Sander
– Sander, Commented Mar 8, 2013 at 19:03

CodeZombie · Accepted Answer · 2014-04-15 15:17:04Z

1

Here you would need to specify a default value for extid:

public HttpResponseMessage GetMessageByCategoryExtId(
    string category, string extid **= null**)

if the above default value is not specified, webapi tries to do a strict matching of an action's parameters with available values(via route parameters or query string values) and since here your url here /api/cat/orders/ does not have a value for 'extid', it isn't present in the route values and hence webapi cannot match to GetMessageByCategoryExtId.

edited Apr 15, 2014 at 15:17

CodeZombie

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answered Mar 15, 2013 at 16:05

Kiran

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