MVC API controller error with dependency injection

Question

i have a simple controller where i am using the interfaec like this ,

public class HomeController : Controller
{
    // GET: Home
    private IHotelService hotelService;
    public HomeController(IHotelService _hotelService)
    {
        hotelService = _hotelService;
    }
}

its working fine, but when i use same thing with API controller like

public class RoomController : BaseApiController
{
    private IHotelService hotelService;
    public RoomController(IHotelService _hotelService)
    {
        hotelService = _hotelService;
    }

it gives me error

Answer 1

As pointed out here (and in several other answers on SO), you have most likely not registered your DI container with Web API. Web API is a separate framework than MVC and therefore it has a separate configuration, including dependency injection.

So, you need to set

GlobalConfiguration.Configuration.DependencyResolver = MyDependencyResovler(container);

at application startup. The details of how to do this depend on what container you are actually using and whether you use a stock dependency resolver or roll your own as shown in Dependency Injection in ASP.NET Web API 2.