public async Task <IActionResult> Index(string buyerKey) { var spec = string.IsNullOrEmpty(buyerKey) ? BaseSpecification <Order> .Create(i => true) : BaseSpecification <Order> .Create(i => i.BuyerId.Contains(buyerKey)); spec.AddInclude("OrderItems($select=UnitPrice,Units)"); var orders = await orderRepository.ListAsync(spec); ViewBag.buyerKey = buyerKey; return(View(orders.OrderByDescending(i => i.OrderDate))); }