Question

I have the following:

public interface ICartItem
{
    string Name { get; set; }
}

public class CartItem : ICartItem
{
    public string Name { get; set; }
}

I then create a List and cast it to an interface:

IList<CartItem> items = new List<CartItem>()
{
    new CartItem() { Name = "MyItem" }
};

IList<ICartItem> cartItems = items.Cast<ICartItem>().ToList();

Is there a way to cast it back again like illustrated below?

IList<CartItem> newList = cartItems as IList<CartItem>;

Answer 1

Do you need a copy of the list?

If yes, and you are sure that there are only CartItems within the list you can do it with

IList<CartItem> newList = cartItems.Cast<CartItem>().ToList();

But i think you’d like it a little more robust. In that case you can try it with

cartItems.Where(item => item as CartItem != null).Cast<CartItem>().ToList();

But i think you need to create a new list. I can’t think of a way to work on the same with an IList interface (IEnumerable<T> works as shown above).