Autofac in MVC 5 - asp.net

Question

I'm trying to learn how to use autofac in MVC and not having a great deal of luck.
I installed Autofac.mvc5 from Nuget version 4.01
and Autofac v4.6.1
I have the following controller:
[Authorize]
public class NotificationsController : ApiController
{
private ApplicationDbContext _context;
private readonly IMapper _mapper;
public NotificationsController(IMapper notificationMapper)
{
_context = new ApplicationDbContext();
_mapper = notificationMapper;
}
public IEnumerable<NotificationDto>GetNewNotifications()
{
var userId = User.Identity.GetUserId();
var notifications = _context.UserNotifications
.Where(un => un.UserId==userId)
.Select(un=>un.Notification)
.Include(n=>n.Gig.Artist).ToList();
return notifications.Select(notification => _mapper.Map<NotificationDto>(notification)).ToList();
}
}
My Global.Asax is:
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
ConfigureAutofac();
GlobalConfiguration.Configure(WebApiConfig.Register);
AreaRegistration.RegisterAllAreas();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
}
private void ConfigureAutofac()
{
var autoMapperConfig = new MapperConfiguration(c =>
{
c.AddProfile(new NotificationProfile());
});
var mapper = autoMapperConfig.CreateMapper();
var builder = new ContainerBuilder();
builder.RegisterInstance(mapper);
builder.Register(x => new NotificationsController(x.Resolve<IMapper>()));
var container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}
}
What I'm finding is that when I call this using postman I get an error saying I need a parameterless consturctor, but then if I put in the constructor _mapper is null.
Could someone point me in the right direction please?

Answer 1

Your controller derives from ApiController, so you are not using MVC, you are using WebApi (I assume WebApi2). So, you should use either Controller and MVC, or install Autofac.WebApi2 NuGet package to handle WebApi2.
Also, instead of registering all your controllers manually, you could use RegisterControllers() for MVC or RegisterApiControllers() for WebApi to have all your controllers registered at once. Especially, when your NotificationController does not use any fancy injection to require more custom registration.
The documentation describes very well, how you should use Autofac with MVC or WebApi, you should start there.