How to use ninject dependency injection in mvc

Overview

While working on MVC application in asp.net sometime we need to inject dependency also know as DI(Dependency Injection).

DI is itself a separate topic to study which I left for some other day. Refer here for more info on DI Dependency Injection

According to the wikipedia

In software engineering, dependency injection is a software design pattern that implements inversion of control for resolving dependencies. A dependency is an object that can be used (a service). An injection is the passing of a dependency to a dependent object (a client) that would use it.

To inject dependencies we have DI librabry like Ninject ,Unity

In this article I am going to explain how to Add Ninject in our project and how to use.

What I have used is VS2013.

I have entity Product

Now I am creating Interface

Now I need to implement this interface . To implement that I have creating new class ProductRepository

Now I want to inject dependency but for that I need download some nuget package

1. Ninject
2. Ninject.Web.Common
3. Ninject.Web.MVC
4. WebActivator

When this Ninject.Web.Common dll is added a new class file “NinjectWebCommon.cs” will be added in

AppStart

with these information

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(ShoppingApi.App_Start.NinjectWebCommon), “Start”)]
[assembly: WebActivatorEx.ApplicationShutdownMethodAttribute(typeof(ShoppingApi.App_Start.NinjectWebCommon), “Stop”)]

namespace ShoppingApi.App_Start
{
using System;
using System.Web;

using Microsoft.Web.Infrastructure.DynamicModuleHelper;

using Ninject;
using Ninject.Web.Common;

public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();

/// <summary>
/// Starts the application
/// </summary>
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}

/// <summary>
/// Stops the application.
/// </summary>
public static void Stop()
{
bootstrapper.ShutDown();
}

/// <summary>
/// Creates the kernel that will manage your application.
/// </summary>
/// <returns>The created kernel.</returns>
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
try
{
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

RegisterServices(kernel);
return kernel;
}
catch
{
kernel.Dispose();
throw;
}
}

/// <summary>
/// Load your modules or register your services here!
/// </summary>
/// <param name=”kernel”>The kernel.</param>
private static void RegisterServices(IKernel kernel)
{
System.Web.Mvc.DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
}
}
}

In RegisterServices method I need to add register my dependency. That I have done in

my class NinjectDependencyResolver by implementing interface IdependencyResolver

the class would be like

using Ninject;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace ShoppingApi.InfraStructure
{
public class NinjectDependencyResolver:IDependencyResolver
{
IKernel kernel = null;
public NinjectDependencyResolver(IKernel kernelParam ){
kernel=kernelParam;
AddBinding();
}

private void AddBinding()
{
kernel.Bind<IProductRepository>().To<EFProductRepository>();
}
public object GetService(Type serviceType)
{
return kernel.TryGet(serviceType);
}

public IEnumerable<object> GetServices(Type serviceType)
{
return kernel.GetAll(serviceType);
}
}
}

In AddBinding() method add the binding you want to add.

Now I want to use in my controller.  I have use Parametrized constructor to set the value

public class AdminController : Controller
{
private IProductRepository repository;

public AdminController(IProductRepository prodRepository)
{
repository = prodRepository;
}

// GET: Admin
//[AllowAnonymous]
public ActionResult Index()
{

return View(repository.Products);
}

public ViewResult Edit(int productID)
{
var product=repository.Products.FirstOrDefault(p=>p.ProductId.Equals(productID));
return View(product);
}

public ViewResult AddNewItem()
{
return View();
}

[HttpPost]
public ActionResult AddNewItem(Product product)
{
if(ModelState.IsValid){
repository.SaveProduct(product);
TempData[“Message”] = string.Format(“Item {0} is successfully Added”, product.Name);
return RedirectToAction(“Index”);
}
else {
TempData[“Message”] = string.Format(“Item {0} is not Added”, product.Name);
return View(product);
}

}

[HttpPost]
public ActionResult Edit(Product product)
{
if (ModelState.IsValid)
{
repository.SaveProduct(product);
TempData[“Message”] = string.Format(“Item {0} is successfully saved”, product.Name);
return RedirectToAction(“Index”);
}
else
{
return View(product);
}
}

[HttpPost]
public ActionResult Delete(int productID)
{
Product deleteProduct = repository.DeleteProduct(productID);
if (deleteProduct != null)
{
TempData[“Message”] = string.Format(“Item {0} is successfully Deleted”, deleteProduct.Name);

}
return RedirectToAction(“Index”);
}
}

Yes its that easy to implement. Hope that helpful for you.

Note: In WebApi we can also use Ninject but it is not the same way . This is for next article