我希望能够查询父实体并过滤子集合的内容。
例如,我有一个OrderHeaders集合。我想使用LINQ查询此集合以返回所有OrderHeaders,但我只想要包含一些相关的OrderDetail行。
我最好寻找一个解决方案,我可以在一个LINQ语句中完成所有这些。
以下控制台应用程序演示了这一点。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace LINQ
{
class Program
{
static void Main(string[] args)
{
List<OrderHeader> orders = GetOrderHeaders();
var filteredOrders = from p in orders
where p.Detail.Where(e => e.StockCode == "STK2").Count() > 0
select p;
foreach (var order in filteredOrders)
{
Console.WriteLine("Account {0} ", order.AccountCode);
foreach (var detail in order.Detail)
{
Console.WriteLine("StockCode {0}, Quantity {1}", detail.StockCode, detail.Quantity);
}
Console.WriteLine();
}
// The above will return the following:
// Account CUST1
// StockCode STK1, Quantity 1
// StockCode STK2, Quantity 2
//
// Account CUST2
// StockCode STK2, Quantity 1
// StockCode STK4, Quantity 2
// How can I get the following?
// Account CUST1
// StockCode STK2, Quantity 2
//
// Account CUST2
// StockCode STK2, Quantity 1
Console.ReadLine();
}
public static List<OrderHeader> GetOrderHeaders()
{
List<OrderHeader> orders = new List<OrderHeader>();
OrderHeader header =
new OrderHeader {
AccountCode = "CUST1",
Detail = new List<OrderDetail>()};
header.Detail.Add(
new OrderDetail { StockCode = "STK1", Quantity = 1 });
header.Detail.Add(
new OrderDetail { StockCode = "STK2", Quantity = 2 });
orders.Add(header);
header =
new OrderHeader
{
AccountCode = "CUST2",
Detail = new List<OrderDetail>()
};
header.Detail.Add(
new OrderDetail { StockCode = "STK2", Quantity = 1 });
header.Detail.Add(
new OrderDetail { StockCode = "STK4", Quantity = 2 });
orders.Add(header);
return orders;
}
}
public class OrderHeader
{
public string AccountCode { get; set; }
public List<OrderDetail> Detail {get; set;}
}
public class OrderDetail
{
public string StockCode { get; set; }
public int Quantity { get; set; }
}
}
非常感谢任何建议。
保
答案 0 :(得分:19)
尝试以下方法:
var filtered = orders
.Where(o => o.Detail.Any(d => d.StockCode == "STK2"))
.Select(o => new { Order = o, Details = o.Detail.Where(d => d.StockCode == "STK2") });
然后可以这样使用:
foreach (var entity in filtered)
{
Console.WriteLine("Account {0} ", entity.Order.AccountCode);
foreach (var detail in entity.Details)
{
Console.WriteLine("StockCode {0}, Quantity {1}", detail.StockCode, detail.Quantity);
}
Console.WriteLine();
}