Question

This is just something I’ve been thinking about and was wondering if it exists, or even if its beneficial at all.

I’m doing inversion of control and dependency injection using Unity. I’m also doing ORM with fluent nHibernate. I was wondering if there was a way to either configure nHibernate to take interfaces as its type parameters and do IoC for me, or what the best way to use them together would be.

For instance, if I had a customer object using a repository pattern I would possibly have 2 interfaces (ICustomer, ICustomerRepository) as well as 2 concrete implementations (Customer, CustomerRepository). In the concrete CustomerRepository I would have to tie it directly to the Customer object in order to use nHIbernate.

public class CustomerRepository : ICustomerRepository
{
    public ICustomer Retrieve(int id)
    {
        return _session.Get<Customer>(id);
    }
}

Instead of passing “Customer” as a type parameter to the session, I think it would be cool to pass “ICustomer” and somehow have nHibernate configured to do the IoC. Is this even possible, or beneficial at all?

Answer 1

When we started designing our application, I had the exact same idea. However, pretty soon we ran into some issues with using only interface based types, so we compromised, by using concrete types and loose repositories, meaning Customer and ICustomerRepository.

I’m trying to recall what issues we ran into, but right now I’m blanked out.