Question

在下面的代码中，我有一个代表订单的对象列表Line。由于订单可以包含多个产品，因此我可以按订单号对这些对象进行分组。下面的代码按订单号对所有行对象进行分组，我创建了一个名为ServiceOrder的对象实例。 ServiceOrder有订单号，我将该订单的所有产品绑定到List<Line>。

在我的代码中，它是一个两步过程，我首先对所有Line个对象进行分组，然后迭代该组以创建List<ServiceOrder>个对象。

使用linq，可以使用1行语句完成，例如一步？

输出

Order: A1234
1. Widget 2
2. Sproket 2
3. Wobble 2

代码：

Line o1 = new Line { OrderNumber = "A1234", Description = "Widget", Qty = 2 };
Line o2 = new Line { OrderNumber = "A1234", Description = "Sproket", Qty = 2 };
Line o3 = new Line { OrderNumber = "A1234", Description = "Wobble", Qty = 2 };
Line o4 = new Line { OrderNumber = "A98745", Description = "Cog", Qty = 2 };
List<Line> incomingOrders = new List<Line>();
incomingOrders.Add(o1);
incomingOrders.Add(o2);
incomingOrders.Add(o3);
incomingOrders.Add(o4);

List<ServiceOrder> serviceOrders = new List<ServiceOrder>();

var orderGrouped = incomingOrders.Select((value, index) => new { obj = value, idx = index })
                 .GroupBy(order => order.obj.OrderNumber).Select(grp => grp.Select(g => g.obj).ToList()).ToList();

foreach (var grp in orderGrouped)
{
    ServiceOrder serviceOrder = new ServiceOrder();
    var firstOrder = grp.First();
    serviceOrder.OrderNumber = firstOrder.OrderNumber;                
    serviceOrder.Orders = grp;
    serviceOrders.Add(serviceOrder);

}


// print out
foreach (var order in serviceOrders) {

    System.Diagnostics.Debug.WriteLine("Order: " + order.OrderNumber);
    int num = 1;
    foreach (var line in order.Orders) {

        System.Diagnostics.Debug.WriteLine(String.Format("{0}. {1} {2}", num, line.Description, line.Qty));
        num++;
    }

}

public class ServiceOrder
{
    public List<Line> Orders { get; set; }      
    public String OrderNumber { get; set; }

}

public class Line {

    public int Qty { get; set; }
    public String Description { get; set; }
    public String OrderNumber { get; set; }
}

Answer 1

使用IGrouping.Key属性：

List<ServiceOrder> serviceOrders =
    incomingOrders.GroupBy(o => o.OrderNumber)
                  .ToList(g => new ServiceOrder() {
                                       OrderNumber = g.Key,
                                       Orders = g.ToList() });

PS。当你以后根本没有使用它时，为什么要在你的枚举中引入索引？

在一个语句中对对象进行分组和构建

1 个答案: