How to create dependency injection for ASP.NET MVC 5?

Question

Creating Dependency Injection with ASP.NET Core is fairly easy. The documentation explains it very well here and this guy has a killer video to explain it.

However,

Answer 1

For this answer I downloaded a Microsoft Example of WebApi project as a basis for the example and added DI services to it as follows,

• Update the Target Framework to 4.6.1
• NuGet the DI package :- Microsoft.Extensions.DependencyInjection

After the standard MapHttpRoute configuration, add code to register which services you need

using's

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using Microsoft.Extensions.DependencyInjection;
using System.Web.Http.Dependencies;
using ProductsApp.Controllers;

WebApiConfig

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Web API routes
        config.MapHttpAttributeRoutes();

        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

        // create the DI services and make the default resolver
        var services = new ServiceCollection();
        services.AddTransient(typeof(DefaultProduct));
        services.AddTransient(typeof(ProductsController));

        var resolver = new MyDependencyResolver(services.BuildServiceProvider());
        config.DependencyResolver = resolver;
    }
}

DefaultProduct

public class DefaultProduct : ProductsApp.Models.Product
{
    public DefaultProduct()
    {
        this.Category = "Computing";
        this.Id = 999;
        this.Name = "Direct Injection";
        this.Price = 99.99M;
    }
}

MyDependencyResolver

/// <summary>
/// Provides the default dependency resolver for the application - based on IDependencyResolver, which hhas just two methods.
/// This is combined dependency resolver for MVC and WebAPI usage.
/// </summary>
public class MyDependencyResolver : System.Web.Mvc.IDependencyResolver, System.Web.Http.Dependencies.IDependencyResolver 
{
    protected IServiceProvider serviceProvider;
    protected IServiceScope scope = null;

    public MyDependencyResolver(IServiceProvider serviceProvider) 
    {
        this.serviceProvider = serviceProvider;
    }

    public MyDependencyResolver(IServiceScope scope) 
    {
        this.scope = scope;
        this.serviceProvider = scope.ServiceProvider;
    }

    public IDependencyScope BeginScope() 
    {
        return new MyDependencyResolver(serviceProvider.CreateScope());
    }

    public void Dispose() 
    {
        Dispose(true);
    }

    protected virtual void Dispose(bool disposing) 
    {
        scope?.Dispose();
    }

    public object GetService(Type serviceType) 
    {
        return this.serviceProvider.GetService(serviceType);
    }

    public IEnumerable<object> GetServices(Type serviceType) 
    {
        return this.serviceProvider.GetServices(serviceType);
    }
}

ServiceProviderExtensions

public static class ServiceProviderExtensions
{
    public static IServiceCollection AddControllersAsServices(this IServiceCollection services, IEnumerable<Type> serviceTypes)
    {
        foreach (var type in serviceTypes)
        {
            services.AddTransient(type);
        }

        return services;
    }
}

I then amended the existing controller to take the DI type (note there is just the one ctor)

using ProductsApp.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace ProductsApp.Controllers
{
    public class ProductsController : ApiController
    {
        DefaultProduct _dp = null;

        public ProductsController(DefaultProduct dp)
        {
            _dp = dp;
            //
            products.Add(dp);
        }

        List<Product> products = new List<Product>()
        {
            new Product { Id = 1, Name = "Tomato Soup", Category = "Groceries", Price = 1 },
            new Product { Id = 2, Name = "Yo-yo", Category = "Toys", Price = 3.75M },
            new Product { Id = 3, Name = "Hammer", Category = "Hardware", Price = 16.99M }
        };

        public IEnumerable<Product> GetAllProducts()
        {
            return products;
        }

        public IHttpActionResult GetProduct(int id)
        {
            var product = products.FirstOrDefault((p) => p.Id == id);
            if (product == null)
            {
                return NotFound();
            }
            return Ok(product);
        }
    }
}

Answer 2

I recommend you use Autofac, there are anothers fwk like unity, ninject, the benchmarks autofac has excelent perfomance.

http://www.palmmedia.de/blog/2011/8/30/ioc-container-benchmark-performance-comparison

Here is the integration with MVC (and works with all class)

http://docs.autofac.org/en/latest/integration/mvc.html

Answer 3

From here https://scottdorman.blog/2016/03/17/integrating-asp-net-core-dependency-injection-in-mvc-4/

this line saved me.

    services.AddControllersAsServices(typeof(Startup).Assembly.GetExportedTypes()
      .Where(t => !t.IsAbstract && !t.IsGenericTypeDefinition)
      .Where(t => typeof(IController).IsAssignableFrom(t) 
       || t.Name.EndsWith("Controller", StringComparison.OrdinalIgnoreCase)));