ASP.NET MVC 2, Ninject 2.2 and no parameterless constructor defined for this object

问题

So I've been spending some time with ASP.NET MVC 2 (currently stuck with using Visual Studio 2008) and have now moved onto using Ninject 2.2 and its MVC integration. I've downloaded Ninject 2.2 and Ninject.Web.Mvc from the following locations:

https://github.com/downloads/ninject/ninject/Ninject-2.2.0.0-release-net-3.5.zip
https://github.com/downloads/ninject/ninject.web.mvc/Ninject.Web.Mvc2-2.2.0.0-release-net-3.5.zip

And referenced them in my MVC 2 project. My Global.asax.cs file looks like this (pretty much what the Ninject.Web.Mvc README says):

using System;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using Ninject.Web.Mvc;
using Ninject;

namespace Mvc2 {
    public class MvcApplication : NinjectHttpApplication {
        public static void RegisterRoutes(RouteCollection routes) {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                    "Default", // Route name
                    "{controller}/{action}/{id}", // URL with parameters
                    new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
            );
        }

        protected override void OnApplicationStarted() {
            AreaRegistration.RegisterAllAreas();
            RegisterRoutes(RouteTable.Routes);
        }

        protected override IKernel CreateKernel() {
            var kernel = new StandardKernel();

            kernel.Bind<IFoo>().To<Foo>();

            return kernel;
        }
    }
}

And a home controller that looks like this:

using System;
using System.Web;
using System.Web.Mvc;

namespace Mvc2.Controllers {
    public class HomeController : Controller {
        private readonly IFoo foo;

        public HomeController(IFoo foo) {
            this.foo = foo;
        }

        public ActionResult Index() {
            ViewData["Message"] = "Welcome to ASP.NET MVC!";

            return View();
        }
    }
}

Now every time I run my project and visit '/' I get a yellow screen of death with a message that says "No parameterless constructor defined for this object." It seems Ninject is not resolving my Foo service and injecting it into HomeController. I imagine I'm missing something really obvious but I'm just not seeing it.

How do I get Ninject to inject Foo into the HomeController, and without using Ninject attributes?

回答1:

Me: Could you provide a little more information about the IFoo service implementation? Does it have all of its own dependencies satisfied?

Myself: Hmm, no it doesn't. Turns out I didn't bind its dependencies. Boy, is that error message and stack trace misleading!

So my mistake was that I didn't bind one of the dependencies of the IFoo implementation and so Ninject failed silently and tried to continue on its merry way. Which is really unfortunate because it could lead to some really strange behavior once I deviate from a trivial setup. I guess my next question should be how can I get Ninject to fail as early as possible and provide good messaging about what's wrong? But for now I can at least get on with it.

来源：https://stackoverflow.com/questions/5765286/asp-net-mvc-2-ninject-2-2-and-no-parameterless-constructor-defined-for-this-obj

标签

asp.net-mvc

asp.net-mvc-2

ninject

ninject-2

ninject.web