AutofacWebApiDependencyResolver method doesnt exist

Question

I am following this tutorial Youtube DI for dependency injection. This clear thing out for me however it does not show how to implement on a Web API using n-tier architecture. I also included followed this tutorial: C-Sharp AutoFac Web API Tutorial.

This is what my code look like:

using Autofac;
using System.Linq;
using System.Reflection;
using System.Web.Http;

namespace WebAPI.App_Start
{
    public class AutofacWebapiConfig
    {

        public static IContainer Container;

        public static void Initialize(HttpConfiguration config)
        {
            Initialize(config, RegisterServices(new ContainerBuilder()));
        }

        public static void Initialize(HttpConfiguration config, IContainer container)
        {
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
        }

        private static IContainer RegisterServices(ContainerBuilder builder)
        {
            //Register your Web API controllers.  
            //builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

            builder.RegisterAssemblyTypes(Assembly.Load(nameof(Coordination)))
              .Where(t => t.Namespace.Contains("Services"))
              .As(t => t.GetInterfaces().FirstOrDefault(i => i.Name == "I" + t.Name));

            //Set the dependency resolver to be Autofac.  
            Container = builder.Build();

            return Container;
        }

    }
}

The issues I have here is that AutofacWebApiDependencyResolver is missing.

And this is where I place my code to call the AutofacWebapiConfig class

namespace CB.WebAPI
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API configuration and services

            //Dependency Injection
            //Configure AutoFac  
            AutofacWebapiConfig.Initialize(GlobalConfiguration.Configuration);

            // Web API routes
            ...
        }
    }
}

This is a brand new web api core with 3 class library doing a n-tier architecture. Any help would be appreciated. Is it at the right location to call it, do I need to create a third class.

I also added a classed Bootstrapper in my app_start folder, and I modified Global.asax to add a line Bootstrapper.Run();

Answer 1

In the comments you have said that the namespace AutofacWebApiDependencyResolver belongs to (Autofac.Integration.WebApi) doesn't exist when you try and add a using directive for it.

It would appear that your project doesn't have the Autofac.Webapi2 NuGet package installed.

To install it using Visual Studio:

1. Select Tools | NuGet Package Manager | Manage NuGet packages for solution...
2. Click the Browse tab
3. Type Autofac.Webapi2 and hit enter/return
4. Click Autofac.WebApi2 from the list
5. Select the project to install it to on the right
6. Click Install
7. OK any licence agreements that appear (assuming you agree).

Alternatively, in Visual Studio 2019 you install it with this simple procedure:

1. Click AutofacWebApiDependencyResolver
2. Ctrl+.
3. Select "Install package 'Autofac.WebApi2'"
4. Click "Find and install latest version"