Question

I’m using NInject in my ASP.NET MVC application and I’m not 100% sure how the singleton is working when creating my Object context.

My Question is:

Using the code below will there be one
ObjectContext per user session or will
there be one that is share for the
entire application? I want each user
to have only one context at one time,
but each user must have their own
instance.

Is InRequestScope() something I should be considering?

I also do the same thing with a WCF service and I assume the answer will be same for both.

My Global.asax:

public class MvcApplication : NinjectHttpApplication
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Change", action = "Index", id = UrlParameter.Optional } // Parameter defaults
        );
    }

    protected override void OnApplicationStarted()
    {
        // Ninject Code
        base.OnApplicationStarted();
        AreaRegistration.RegisterAllAreas();
        RegisterRoutes(RouteTable.Routes);
    }

    protected override IKernel CreateKernel()
    {
        var modules = new INinjectModule[] { new ContextModule() };
        return new StandardKernel(modules);
    }

    public class ContextModule : NinjectModule
    {
        public override void Load()
        {
            Bind<ObjectContext>().To<ChangeRoutingEntities>().InSingletonScope();
            Bind<IObjectContext>().To<ObjectContextAdapter>();
            Bind<IUnitOfWork>().To<UnitOfWork>();
        }
    }
}

Answer 1

ISingletonScope is an application wide scope.
InRequestScope is only for the current request.

You need a session scope. See http://iridescence.no/post/Session-Scoped-Bindings-With-Ninject-2.aspx for a way to implement this type of scope.

public static class NinjectSessionScopingExtention
{
    public static void InSessionScope<T>(this IBindingInSyntax<T> parent)
    {
        parent.InScope(SessionScopeCallback);
    }

    private const string _sessionKey = "Ninject Session Scope Sync Root";
    private static object SessionScopeCallback(IContext context)
    {
        if (HttpContext.Current.Session[_sessionKey] == null)
        {
            HttpContext.Current.Session[_sessionKey] = new object();
        }

        return HttpContext.Current.Session[_sessionKey];
    }
}