Question

Entity Framework 4, Ninject 3, MVC3
Currently in my web app i have been using a rather rudimentary approach to per request instantiation of an Object Context. So I am experimenting with Ninject, and some old sample code, but I am unsure how to proceed with the following..
Effectively I want to be able in the controller to do the equivalent of: DB_Entities.Current.Albums … Should i be instantiating a StandardKernel every time?
The sample i was looking at was using the following: MvcApplication.Container.Get(); but in Ninject 3 with the App_Start hookup I dont have access to Container..

My attempt to replicate the above line, is failing at runtime.

using MusicStoreEntities;
using Ninject;
using TestMVC3WithIOC.App_Start;
using System.Data.Objects;

namespace TestMVC3WithIOC.Models
{
    public partial class MusicStoreEntities
    {
        public static MusicStoreEntities Current
        {
        get
        {
            using (IKernel kernel = new StandardKernel())
            {
            return (MusicStoreEntities)kernel.Get<ObjectContext>();
            }
        }
        }
    }
}

Also, note, that in App_Start\NinjectWebCommon.cs I have the following modification:

    private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind<ILogger>().To<NLogger>();
        kernel.Bind<ObjectContext>().To<MusicStoreEntities>().InRequestScope();

    } 

Answer 1

Although a workable solution, it seems ill-advised to pass the entire Kernel into a class, because it tends to obscure the classes actual, specific dependencies. A better approach is to pass a factory dependency into your controller’s constructor.

public partial class MusicStoreEntities
{
    private readonly IEntitiesFactory _factory;

    public MusicStoreEntities(IEntitiesFactory factory)
    {
        _factory = factory;
    }
}

IEntitiesFactory has a simple implementation with a single method GetObjectContext().

---

(I believe also the “Unit of Work” pattern is popular at the moment, but I can’t really speak to that as I haven’t used it. Maybe worth looking into.)