Dependency Injection By Using Ninject in Web API

Introduction

In this article, I will show you Dependency Injection in the Web API using Ninject.

The following is the procedure for creating the application.

Step 1

Create a Web API application as in the following:

• Start Visual Studio 2012.
• From the start window Select "Installed" -> "Visual C#" -> "Web".
• Select "ASP.NET MVC4 Web Application" and click on the "Ok" button.
  
  
  

• From the "MVC4 Project" window select "Web API".
  
  
  

• Click on the "OK" button.

Step 2

Add an interface in the model folder.

• In the "Solution Explorer".
• Right-click on the "Model" -> "Add" -> "New Item".
• Select "Installed" -> "Visual C#".
• Select "Interface".
  
  
  

• Click on the "Add" button.

Add the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ninjectAPI.Models
{
    public interface IDetail
    {
        string FullName { get; set; }
    }
}

Step 3

Create a Model Class using the following procedure:

• In the "Solution Explorer".
• Right-click on the Model Folder.
• Select "Add" -> "Class".
• Select "Installed" -> "Visual C#" and select class.
  
  
  

• Click on the "Add" button

Add the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace ninjectAPI.Models
{
    public class Detail : IDetail
    {
        public string FullName
        {
            get
            {
                return "Kamya Nehwal";
            }
            set
            {
                this.FullName = value;
            }
        }
    }
}

Step 4

Now install the Ninject.mvc3 package as in the following:

• In the Tools menu.
• Select "Library Package Manager" -> "Manage NuGet Packages for Solutions ".
• In the search box type "ninject".
  
  
  

• Install the Ninject.MVC3 package.
• After installation select the "App_Start" folder; there is a "NinjectWebCommon.cs" class that exists.
  
  
  

Now select this class and perform some changes in the "RegisterServices()" method.

private static void RegisterServices(IKernel kernel)
{
    kernel.Bind<IDetail>().To<Detail>();
}

Step 5

Now add the "Ninject.WebApi.DependencyResolver" as in the following:

• In the Tools menu.
• Select "Library Package Manager" -> "Manage NuGet Packages for Solutions ".
• In the search box type "Ninject.WebApi.DependencyResolver".
  
  
  

• And install the "Ninject.WebApi.DependencyResolver" package.

After installing it, go to the "NinjectWebCommon.cs" file and add the following code in the CreateKernel() method.

private static IKernel CreateKernel()
{
    var kernel = new StandardKernel();
    kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
    kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
    System.Web.Http.GlobalConfiguration.Configuration.DependencyResolver = new Ninject.WebApi.DependencyResolver.NinjectDependencyResolver(kernel);
    RegisterServices(kernel);
    return kernel;
}

Step 6

Add a Controller class in the controller folder as in the following:

• In the "Solution Explorer".
• Right-click on the Controller folder.
• Select "Add" -> "Controller".
  
  
  

• Click on the "Add" button.

Add the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using ninjectAPI.Models;
namespace ninjectAPI.Controllers
{
    public class ShowController : ApiController
    {
        private IDetail idetail = null;
       public ShowController(IDetail Idetail)
       {
           idetail = Idetail;
       }
       [HttpGet]
       public string GetValue()
       {
           return idetail.FullName;
       }
   }
}

Step 7

Execute the application and change the URL to "http://localhost:13357/api/Show/GetValue".