I’ve been spending today moving Suteki Shop to MVC 3. One of the cool new features of MVC 3 is a much greater focus on allowing the various components (Controllers, Views, Filters etc) to be composed by an IoC container. It’s been possible since MVC 1 to provide your own custom controller factory, but the promise with MVC 3 is that you can provide an implementation of IDependencyResolver that wraps your IoC container of choice, and no longer have to bother about implementing various factory classes.

Here’s IDependencyResolver:

public interface IDependencyResolver {
    object GetService(Type serviceType);
    IEnumerable<object> GetServices(Type serviceType);
}

But there’s a huge problem with this. Can you spot it? That’s right, no ‘Release’ method. You can provide a service from your IoC container, but there’s no way to clean it up. If I was going to use this in Suteki Shop, I would have a memory leak of epic proportions.

According to the MVC team, this isn’t an issue because they will call ‘Dispose’ on any service that implements IDisposable, but that won’t work in many cases. Let me explain. Say I’ve got a controller like this:

public class HomeController : IController
{
    private readonly ICustomerRepository customerRepository;
    public HomeController(ICustomerRepository customerRepository)
    {
        this.customerRepository = customerRepository;
    }
    // ... does some stuff with customerRepository
}

public class CustomerRepository : ICustomerRepository, IDisposable
{
    // ... etc
}