UriPathExtensionMapping to control response format in WebAPI - asp.net-web-api

Question

I'm having a problem getting UriPathExtensionMapping working in ASP.NET WebAPI. My setup is as follows:
My routes are:
config.Routes.MapHttpRoute(
name: "Api UriPathExtension",
routeTemplate: "api/{controller}.{extension}/{id}",
defaults: new { id = RouteParameter.Optional }
);
config.Routes.MapHttpRoute(
name: "Api UriPathExtension ID",
routeTemplate: "api/{controller}/{id}.{extension}",
defaults: new { id = RouteParameter.Optional }
);
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
My Global ASAX file is:
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
My Controller is:
public IEnumerable<string> Get()
{
return new string[] { "Box", "Rectangle" };
}
// GET /api/values/5
public string Get(int id)
{
return "Box";
}
// POST /api/values
public void Post(string value)
{
}
// PUT /api/values/5
public void Put(int id, string value)
{
}
// DELETE /api/values/5
public void Delete(int id)
{
}
When making requests using curl, JSON is the default response, even when I explicitly request XML I still get JSON:
curl http://localhost/eco/api/products/5.xml
Returns:
"http://www.google.com"
Can anyone see the problem with my setup?
The following code maps the extensions in the Global.asax file after the routes have been configured:
GlobalConfiguration.Configuration.Formatters.JsonFormatter.
MediaTypeMappings.Add(
new UriPathExtensionMapping(
"json", "application/json"
)
);
GlobalConfiguration.Configuration.Formatters.XmlFormatter.
MediaTypeMappings.Add(
new UriPathExtensionMapping(
"xml", "application/xml"
)
);

Answer 1

Do you need to register the extension mapping like so:
config.Formatters.JsonFormatter.MediaTypeMappings.Add(new UriPathExtensionMapping("json", "application/json"));
config.Formatters.XmlFormatter.MediaTypeMappings.Add(new UriPathExtensionMapping("xml", "application/xml"));
Example was found here.
Update
If you look at the code for UriPathExtensionMapping the placeholder for the extension is
/// <summary>
/// The <see cref="T:System.Uri"/> path extension key.
/// </summary>
public static readonly string UriPathExtensionKey = "ext";
So your routes would need to be changed to ({ext} not {extension}):
config.Routes.MapHttpRoute(
name: "Api UriPathExtension",
routeTemplate: "api/{controller}.{ext}/{id}",
defaults: new { id = RouteParameter.Optional }
);

Answer 2

As an addendum to this answer, because I can't comment yet, you should also make sure your web.config contains the line
<modules runAllManagedModulesForAllRequests="true" />
inside the <system.webServer> section.
Mine didn't and this example didn't work for me until I added that line.