
## Table of Contents

1. [Introduction](#introduction)
2. [packages.config](#packagesconfig)
3. [Startup Class](#startup-class)
4. [API Controller Class: TestController](#api-controller-class-testcontroller)
5. [Interface](#interface)
6. [Class Implementing Interface](#class-implementing-interface)
7. [Autofac Service Module](#autofac-service-module)
8. [Conclusion](#conclusion)

## Introduction

This blog shows how to set up Autofac for dependency injection in ASP.NET Web API 2 with Owin.

## packages.config

Following is the packages.config. You can use this NuGet command to install all
of these to your project: `Update-Package -ProjectName MyProject -reinstall`

```
<?xml version="1.0" encoding="utf-8"?>















```

## Startup Class

```
using Autofac;
using Autofac.Integration.WebApi;
using Microsoft.Owin;
using Owin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web;
using System.Web.Compilation;
using System.Web.Http;
using WebApplication2.Controllers;

[assembly: OwinStartup(typeof(WebApplication2.Startup))]
namespace WebApplication2
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            HttpConfiguration config = new HttpConfiguration();
            // register api routing.
            WebApiConfig.Register(config);
            app.UseWebApi(config);

            var builder = new ContainerBuilder();

            var assemblies = BuildManager.GetReferencedAssemblies().Cast().ToArray();

            builder.RegisterAssemblyModules(assemblies);
            builder.RegisterApiControllers(assemblies);

            var container = builder.Build();
            config.DependencyResolver = new AutofacWebApiDependencyResolver(container);

            app.UseAutofacMiddleware(container);
            app.UseAutofacWebApi(config);
            app.UseWebApi(config);
        }
    }
}
```

## API Controller Class: TestController

```
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace WebApplication2.Controllers
{
    public class TestController : ApiController
    {
        Interface1 _i;
        public TestController(Interface1 i)
        {
            _i = i;
        }

        public IHttpActionResult Get()
        {

            return Ok(new List() { "Hi", "I", "'m", "Just", "testing" });
        }
    }
}
```

## Interface

```
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WebApplication2
{
    public interface Interface1
    {
        string Do();
    }
}
```

## Class Implementing Interface

```
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace WebApplication2
{
    public class Class1 : Interface1
    {
        public string Do()
        {
            return Guid.NewGuid().ToString();
        }
    }
}
```

## Autofac Service Module

```
using Autofac;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace WebApplication2
{
    public class ServiceModule : Module
    {
        protected override void Load(ContainerBuilder builder)
        {
            builder.RegisterType().As().InstancePerDependency();
        }
    }
}
```

## Conclusion

With Autofac and Owin, you can easily set up dependency injection in your ASP.NET Web API 2 project. The key steps are configuring the Owin startup class, registering your controllers and services with Autofac, and creating service modules for your dependency bindings.


How to set up ASP.NET Web API 2 with Autofac and Owin for dependency injection.

Autofac

ASP.NET Web API 2 with Autofac Owin