Generic <T> how cast?

Question

I have a "Product" base class, some other classes "ProductBookDetail","ProductDVDDetail" inherit from this class. I use a ProductService class to make operation on these classes. But, I have to do some check depending of the type (ISBN for Book, languages for DVD). I'd like to know the best way to cast "productDetail" value, I receive in SaveOrupdate. I tried GetType() and cast with (ProductBookDetail)productDetail but that's not work.

Thanks,

var productDetail = new ProductDetailBook() { .... };
var service = IoC.Resolve<IProductServiceGeneric<ProductDetailBook>>();
service.SaveOrUpdate(productDetail);

var productDetail = new ProductDetailDVD() { .... };
var service = IoC.Resolve<IProductServiceGeneric<ProductDetailDVD>>();
service.SaveOrUpdate(productDetail);


public class ProductServiceGeneric<T> : IProductServiceGeneric<T>
{
    private readonly ISession _session;
    private readonly IProductRepoGeneric<T> _repo;
    public ProductServiceGeneric()
    {
        _session = UnitOfWork.CurrentSession;
        _repo = IoC.Resolve<IProductRepoGeneric<T>>();
    }
    public void SaveOrUpdate(T productDetail)
    {            
        using (ITransaction tx = _session.BeginTransaction())
        {
            //here i'd like ot know the type and access properties depending of the class
            _repo.SaveOrUpdate(productDetail);
            tx.Commit();
        }
    }
}

Answer 1

I don't mean to be critical, but that pattern just feels bad to me.

I've heard others say that if you're taking a type in a generic method, then you're most likely doing something wrong.

I would refactor your code by declaring a base class method to help with the SaveOrUpdate method, then have the derived classes override that method. Now when you call the base class method in the generic method, you will get the derived classes implmentation