Autofac in MVC

How to use Autofac?

1. Add Autofac and Autofac.Mvc5 References from NuGet

2. Create ContainerBuilder and register components in application startup

A. Add one line code in Application_Start() function of global.asax file.

  DependencyConfig.RegisterDependencyResolvers();

B. Add the DependencyConfig class in the folder App_Start:

public static class DependencyConfig
{
    public static IContainer RegisterDependencyResolvers()
    {
        ContainerBuilder builder = new ContainerBuilder();
        RegisterDependencyMappingDefaults(builder);
        RegisterDependencyMappingOverrides(builder);
        IContainer container = builder.Build();
        // Set Up MVC Dependency Resolver
        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
        // Set Up WebAPI Resolver
        GlobalConfiguration.Configuration.DependencyResolver = new AutofacWebApiDependencyResolver(container);
        return container;
    }

    private static void RegisterDependencyMappingDefaults(ContainerBuilder builder)
    {
        Assembly coreAssembly = Assembly.GetAssembly(typeof(IStateManager));
        Assembly webAssembly = Assembly.GetAssembly(typeof(MvcApplication));

        builder.RegisterAssemblyTypes(coreAssembly).AsImplementedInterfaces().InstancePerRequest();
        builder.RegisterAssemblyTypes(webAssembly).AsImplementedInterfaces().InstancePerRequest();

        builder.RegisterControllers(webAssembly);
        builder.RegisterModule(new AutofacWebTypesModule());
    }

    private static void RegisterDependencyMappingOverrides(ContainerBuilder builder)
    {
        // builder.RegisterType<WebSettingManager>().AsImplementedInterfaces().SingleInstance();
        builder.RegisterType<SearchDataService>().As<ISearchDataService>();
    }
}

3. Add Interface

    public interface ISearchDataService
    {
        string CombineConfirmedCasesDailyCountURL(string postcode);
    }

4. Add Service code

    public class SearchDataService : ISearchDataService
    {
        public string CombineConfirmedCasesDailyCountURL(string postcode)
        {
            string part1 = ConfigurationManager.AppSettings["ConfirmedCasesByPostcode1"];
            string part2 = ConfigurationManager.AppSettings["ConfirmedCasesByPostcode2"];
            return part1 + " '" + postcode + "' " + part2;
        }
    }

5. Call service in the controller

    public class HomeController : Controller 
    {
        private readonly ISearchDataService _searchDataService;

        public HomeController(ISearchDataService iSearchDataService)
        {
            // Injected from Autofac
            _searchDataService = iSearchDataService;
        }


        [HttpPost]
        public ActionResult Index(RetrieveDataViewModel model)
        {
            if (!ModelState.IsValid)
                return View(model);

            string webAddress = _searchDataService.CombineConfirmedCasesDailyCountURL(model.Postcode);
            model.DailyCountResult = _searchDataService.GetCasesDailyCountList(webAddress);

            return View(model);
        }

     } 

 public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.MapHttpAttributeRoutes();

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

Reference:

https://dependencyinjector.wordpress.com/2014/12/19/setting-up-dependency-injection-in-asp-net-mvc-with-autofac/https://www.codeproject.com/Articles/808894/IoC-in-ASP-NET-MVC-using-Autofac