Ninject and ASP.NET Web API

Question

Before I set up the question you should know that I got my current code from this page: http://www.strathweb.com/2012/05/using-ninject-with-the-latest-asp-net-web-api-source/

I'm trying to use ASP.NET Web API and Ninject in my application by using an IDependencyResolver adapter found on the site above.

I created all the code just like it shows on the site and it works but when I load up my appication my regular controllers fail and show this error:

[MissingMethodException: No parameterless constructor defined for this object.]
[InvalidOperationException: An error occurred when trying to create a controller of type 'AccountManager.Controllers.HomeController'...

So, it seems like I can use Ninject with regular controllers or Web API controllers but not both. :(

Here is my code:

NinjectResolver.cs

public class NinjectResolver : NinjectScope, IDependencyResolver
{
    private IKernel _kernel;

    public NinjectResolver(IKernel kernel)
        : base(kernel)
    {
        _kernel = kernel;
    }

    public IDependencyScope BeginScope()
    {
        return new NinjectScope(_kernel.BeginBlock());
    }
}

NinjectScope.cs

public class NinjectScope : IDependencyScope
{
    protected IResolutionRoot resolutionRoot;

    public NinjectScope(IResolutionRoot kernel)
    {
        resolutionRoot = kernel;
    }

    public object GetService(Type serviceType)
    {
        IRequest request = resolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true);
        return resolutionRoot.Resolve(request).SingleOrDefault();
    }

    public IEnumerable<object> GetServices(Type serviceType)
    {
        IRequest request = resolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true);
        return resolutionRoot.Resolve(request).ToList();
    }

    public void Dispose()
    {
        IDisposable disposable = (IDisposable)resolutionRoot;
        if (disposable != null) disposable.Dispose();
        resolutionRoot = null;
    }
}

Global.asax.cs

public class MvcApplication : System.Web.HttpApplication
{
    private void SetupDependencyInjection()
    {
        //create Ninject DI Kernel
        IKernel kernel = new StandardKernel();

        //register services with Ninject DI container
        RegisterServices(kernel);

        //tell asp.net mvc to use our Ninject DI Container
        GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);
    }
}

AccountingController.cs

public class AccountingController : ApiController
{
    private ICustomerService _customerService;

    public AccountingController(ICustomerService service)
    {
        _customerService = service;
    }

    // GET /api/<controller>/5
    public string Get(int id)
    {
        return "value";
    }
}

Not used Ninject before, but is there a reason you can't add a parameterless constructor on the type Ninject is trying to inject into? — Charleh
– Charleh, Commented Jul 25, 2012 at 15:10
@Charleh: That would defeat the purpose of an IoC container. — StriplingWarrior
– StriplingWarrior, Commented Jul 25, 2012 at 15:11

Yasser Shaikh · Accepted Answer · 2012-12-01 16:04:36Z

Insert the following line of code into the CreateKernel() method before the call to the RegisterServices(kernel); is made.

GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);

You will also need to use the below code, I prefer to have it defined in the same class.

public class NinjectResolver : NinjectScope, IDependencyResolver
{
    private IKernel _kernel;
    public NinjectResolver(IKernel kernel)  : base(kernel)
    {
        _kernel = kernel;
    }
    public IDependencyScope BeginScope()
    {
        return new NinjectScope(_kernel.BeginBlock());
    }
}

public class NinjectScope : IDependencyScope
{
    protected IResolutionRoot resolutionRoot;
    public NinjectScope(IResolutionRoot kernel)
    {
        resolutionRoot = kernel;
    }
    public object GetService(Type serviceType)
    {
        IRequest request = resolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true);
        return resolutionRoot.Resolve(request).SingleOrDefault();
    }
    public IEnumerable<object> GetServices(Type serviceType)
    {
        IRequest request = resolutionRoot.CreateRequest(serviceType, null, new Parameter[0], true, true);
        return resolutionRoot.Resolve(request).ToList();
    }
    public void Dispose()
    {
        IDisposable disposable = (IDisposable)resolutionRoot;
        if (disposable != null) disposable.Dispose();
        resolutionRoot = null;
    }
}

Run it, and it should work. This worked for me, I hope it does for you too.

Further Reading :

Using Ninject – Dependency Injection with ASP.NET Web API controllers

Just like many "works for me" tutorials for Ninject, this one is outdated.

Paul Manzotti · Accepted Answer · 2012-07-26 13:43:55Z

I have a Web API project working using exactly the same solution as you from strathweb, so I just added a normal controller to the project, and it does work. Not a great help on it's own for you, so I'll detail the setup I've got:

I have the following packages installed (on the IOC side of things):

Ninject 3.0.1.10
Ninject MVC 3.0.0.6
Ninject.Web.Common 3.0.0.7
WebActivator 1.5.1

I have absolutely nothing in my Global.asax.cs file regarding Ninject, instead using the NinjectWebCommon.cs file that is automatically created in App_Start when you install Ninject. I don't know if by having code in your Global file that means that Ninject hasn't set itself up correctly in your project?

Here is the code in NinjectWebCommon.cs:

    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();
        kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
        kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

        RegisterServices(kernel);

        GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);

        return kernel;
    }

    /// <summary>
    /// Load your modules or register your services here!
    /// </summary>
    /// <param name="kernel">The kernel.</param>
    private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind<IUserRepository>().To<UserRepository>().InSingletonScope();
        kernel.Bind<IUserManager>().To<UserManager>();
    }        
}

Here's the other difference I can see between our code, where I create the Kernel, my code declares two bindings to the kernel.

Here's the code for my test controller, I can set a breakpoint in the constructor and it gets it:

public class TestController : Controller
{
    IUserManager _userManager;

    public TestController(IUserManager userManager)
    {
        _userManager = userManager;
    }

    //
    // GET: /Test/
    public ActionResult Index()
    {
        return View();
    }
}

This works with both my Controller and my APIControllers.

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