Linq使用選擇新值來計算另一個字段

Question

是否有可能在linq中執行以下操作，在我的select new中使用TotalOrderItems的值作爲TotalInStockItems的計算的一部分？

var Order = (from o in orderItems 
      select new ShippingOrder { OrderId = orderItems.OrderId 
             TotalOrderItems = orderItems.GroupBy(x => x.Sku).Count(), 
             TotalInStockItems = TotalOrderItems - orderItems.Where(x => x.InStock =='F').GroupBy(x => x.Sku).Count(), 
             }).ToList(); 

Answer 1

嘗試使用let clause (C# Reference)來使用的值存儲在後面的查詢

(from o in orderItems 
let totalOrderItems = orderItems.GroupBy(x => x.Sku).Count() 
select new ShippingOrder { 
    OrderId = o.OrderId 
    TotalOrderItems = totalOrderItems, 
    TotalInStockItems = totalOrderItems - orderItems.Where(x => x.InStock =='F').GroupBy(x => x.Sku).Count(), 
}).ToList();