Clean Domain-driven Design article - Delete Product in the Cart

RequestHandler.cs

public class RequestHandler : TxRequestHandlerBase<DeleteItemRequest, DeleteItemResponse>
{
  private readonly ICatalogGateway _catalogGateway;
  private readonly IShippingGateway _shippingGateway;
  private readonly IPromoGateway _promoGateway;

  public RequestHandler(IUnitOfWorkAsync uow, IQueryRepositoryFactory qf,
    ICatalogGateway cgw, IShippingGateway shippingGateway, IPromoGateway promoGateway)
    : base(uow, qf)
  {
    _catalogGateway = cgw;
    _shippingGateway = shippingGateway;
    _promoGateway = promoGateway;
  }

  public override async Task<DeleteItemResponse> Handle(DeleteItemRequest request, CancellationToken cancellationToken)
  {
    var cartCommander = UnitOfWork.Repository<Domain.Cart>();
    var cartQuery = QueryFactory.QueryEfRepository<Domain.Cart>();

    var cart = await cartQuery.GetFullCartAsync(request.CartId);
    var cartItem = cart.FindCartItem(request.ProductId);

    cart.RemoveCartItem(cartItem.Id);
    await cart.CalculateCartAsync(TaxType.NoTax, _catalogGateway, _promoGateway, _shippingGateway);

    await cartCommander.UpdateAsync(cart);
    await UnitOfWork.SaveChangesAsync(cancellationToken);

    return new DeleteItemResponse { ProductId = cartItem.Product.ProductId };
  }
}