通過LINQ創建匿名對象

Question

我有一個對象：

public class Ticket
{
   public string EventName {get;set;}
   public string Count {get;set;}
   public string Price {get;set;}
   ... other properties;
}

測試：

var tickets = new List<Ticket>();
tickets.Add(new Ticket {EventName = "Test", TicketCount = 1, Price = 100});
tickets.Add(new Ticket { EventName = "Test", TicketCount = 2, Price = 200 });
tickets.Add(new Ticket { EventName = "Test2", TicketCount = 1, Price = 50 });

我想獲取具有以下屬性的匿名對象： EventName, TicketCount, Price和按事件名稱“分組”。
對於上面的示例，結果必須是：
匿名對象必須包含兩個記錄：

EventName = Test, TicketCount = 3, Price = 300
EventName = Test2, TicketCount = 1, Price = 50

我沒有完成的代碼：

var groupedByEvent = tickets.GroupBy(t => t.EventName);
var obj = new {EventName = seatsByEvent.Select(t=>t.Key), TicketCount = seatsByEvent.Sum(???)}

怎么解決這個？

Answer 1

var result = tickets.GroupBy(t => t.EventName)
                    .Select(g  => new { 
                             EventName = g.Key, 
                             TicketCount = g.Sum(t => t.TicketCount), 
                             Price = g.Sum(t => t.Price)
                    });

foreach(var x in result)
     Console.WriteLine("EventName = {0}, TicketCount = {1}, Price = {2}"
                       , x.EventName , x.TicketCount , x.Price);

Answer 2

var groupedByEvent = tickets.GroupBy(t => t.EventName);

var obj = groupByEvent.Select(group => new {
   EventName = group._Key,
   TicketCount = group.Sum(x => x.TicketCount),
   Price = group.Sum(x => x.Price)
});

Answer 3

首先，你必須正確設置你的POCO課程：

public class Ticket
{
  public string EventName {get;set;}
  public string Count {get;set;}
  public int Price {get;set;}
  public int TicketCount { get; set; }
}

Price必須是和int，也像TicketCount ，這必然是總和。

然后linq查詢將如下所示：

var events = tickets.GroupBy(t => t.EventName).Select(g => new 
{
  EventName = g.Key,
  TicketCount = g.Sum(t => t.TicketCount),
  Price = g.Sum(t => t.Price)
});