[Ninject][ASP NET Web API] A demonstration of Dependency injection on ASP NET Web API's controller using Ninject & Dependency Resolver.

DependencyResolver.cs

using System.Web.Http.Dependencies;

namespace Xtremecode.Infrastructure.Library.Di
{
    public class DependencyResolver : DependencyScope, IDependencyResolver
    {
        public DependencyResolver() : base(DependencyInjector.GetKernel()) { }

        public IDependencyScope BeginScope()
        {
            return new DependencyScope(DependencyInjector.BeginBlock());
        }
    }
}

DependencyScope.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http.Dependencies;

using Ninject.Parameters;
using Ninject.Syntax;

namespace Xtremecode.Infrastructure.Library.Di
{
    public class DependencyScope : IDependencyScope
    {
        public DependencyScope(IResolutionRoot resolutionRoot)
        {
            ResolutionRoot = resolutionRoot;
        }

        protected IResolutionRoot ResolutionRoot { get; set; }

        public void Dispose()
        {
            var disposable = ResolutionRoot as IDisposable;
            if (disposable != null)
            {
                disposable.Dispose();
            }
        }

        public object GetService(Type serviceType)
        {
            return resolveType(serviceType).SingleOrDefault();
        }

        public IEnumerable<object> GetServices(Type serviceType)
        {
            return resolveType(serviceType).ToArray();
        }

        private IEnumerable<object> resolveType(Type serviceType)
        {
            var request = ResolutionRoot.CreateRequest(serviceType, null, new IParameter[0], true, true);
            return ResolutionRoot.Resolve(request);
        }
    }
}

Global.asax.cs

using System.Web.Http;
using System.Web.Mvc;
using System.Web.Routing;

using Xtreme.Gaming.Strore.Web.Controllers;
using DependencyResolver = Xtremecode.Infrastructure.Library.Di.DependencyResolver;

namespace Xtreme.Gaming.Store.Web.Spa
{
    // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
    // visit http://go.microsoft.com/?LinkId=9394801
    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            
            ControllerBuilder.Current.SetControllerFactory(new ControllerFactory());

            // The part that do the magic on the Web Api's Controllers
            GlobalConfiguration.Configuration.DependencyResolver = new DependencyResolver();

            // Web API's Trick #1: Force the any controller's actions to return JSON string
            GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
        }
    }
}

ProductController.cs

using System.Collections.Generic;
using System.Web.Http;

using Xtreme.Gaming.Store.Domain.Models;
using Xtreme.Gaming.Store.Domain.Services;

namespace Xtreme.Gaming.Store.Web.Spa.Controllers
{
    public class ProductController : ApiController
    {
        private readonly IProductService _productService;

        public ProductController(IProductService productService)
        {
            _productService = productService;
        }

        //
        // GET: /SpecialOffers
        [AcceptVerbs("GET")]
        public IEnumerable<Product> SpecialOffers()
        {
            // Get a list of Products which are offered as current discounted items
            var getSpecialOffersResponse = _productService.GetSpecialOffers();
            return getSpecialOffersResponse.IsSuccess ? getSpecialOffersResponse.Products : new Product[0];
        }

    }
}