Aim:

This article explains about how to implement “NInject” framework in MVC application to resolve object dependencies.

There are three types of Injection available in NInject,

1.       Constructor Injection

2.       Property Setter Injection

3.       Method Injection

In this project, we will look into “Constructor” Injection pattern with easy steps,

Step 1:

Create empty MVC Project

Step 2:

Right click the project à Click on “Manage NuGet Packages” à Click on “Browse” and Type “NInject” and search

1.       Install NInject

2.       Install NInject.MVC5

a.       This will install the below components in your solution

                                                               i.      NInject.Web.Common.3.3.0

                                                             ii.      NInject.Web.Common.WebHost.3.3.0

                                                           iii.      NInject.MVC5.3.3.0

Step3:

1.       Global.asax Changes:

a.       Remove “System.Web.HttpApplication” and Inherit “NinjectHttpApplication” as mentioned below.

public class MvcApplication : NinjectHttpApplication

{

 // App Start Methods should come here.

}

b.       Remove “Application_Start” and override the “OnApplicationStarted” Method inside it and place its registration methods.

protected override void OnApplicationStarted()

                  {

                        base.OnApplicationStarted();

                        AreaRegistration.RegisterAllAreas();

                        RouteConfig.RegisterRoutes(RouteTable.Routes);

            DependencyResolver.SetResolver(DependencyResolver.Current.ToServiceResolver());

        }

c.       Override “CreateKernel” Method and load the required assemblies.

  protected override IKernel CreateKernel()

        {

         var kernel = new StandardKernel();

         kernel.Load(Assembly.GetExecutingAssembly(), Assembly.Load("NInjectSample.Models"));

         kernel.Load(Assembly.GetExecutingAssembly(), Assembly.Load("NInjectSample.Business"));

         kernel.Load(Assembly.GetExecutingAssembly(),

Assembly.Load("NInjectSample.Common"));

         return kernel;

     }

Step 4:

1.       Create Dependency Mapper Class by overriding the NInjectModule’s à Load Method

public class DependencyMapper : NinjectModule

    {

        public override void Load()

        {

           this.Bind<IRegistrationManager>().To<RegistrationManager>();

        }

    }

Step 5:

1.       Create “Resolver” Adapter by implementing “IDependencyResolver” to resolve object at run time.

public class ServiceResolverAdapter : IDependencyResolver

    {

        private readonly System.Web.Mvc.IDependencyResolver dependencyResolver;

 

        public ServiceResolverAdapter(

            System.Web.Mvc.IDependencyResolver dependencyResolver)

        {

            if (dependencyResolver == null)

            {

                throw new ArgumentNullException("dependencyResolver");

            }

            this.dependencyResolver = dependencyResolver;

        }

 

        public object GetService(Type serviceType)

        {

            return dependencyResolver.GetService(serviceType);

        }

 

        public IEnumerable<object> GetServices(Type serviceType)

        {

            return dependencyResolver.GetServices(serviceType);

        }

}

2.       Create Service Resolver Extension class

    public static class ServiceResolverExtensions

    {

        public static IDependencyResolver ToServiceResolver(

            this System.Web.Mvc.IDependencyResolver dependencyResolver)

        {

            return new ServiceResolverAdapter(dependencyResolver);

        }

    }

3.       Register it in the Global.asax à “OnApplicationStarted” Method

protected override void OnApplicationStarted()

        {

            base.OnApplicationStarted();

            AreaRegistration.RegisterAllAreas();

            RouteConfig.RegisterRoutes(RouteTable.Routes);

            DependencyResolver.SetResolver(DependencyResolver.Current.ToServiceResolver());

        }

Step 6:

1.       Decorate Controller’s Constructor with [Inject] attribute to inject the required objects based on the registration done in the “DependencyMapper” class.

        [Inject]

        public HomeController(IRegistrationManager registrationManager)

        {

            this._registrationManager = registrationManager;

        }