循环查找 - 将元素串在一起

Question

在 , I have a working linq 查找的帮助下，每个发票都有一个 InvoiceID + 产品列表：

我可以成功循环查找（如代码所示），并显示密钥，但我需要帮助显示每个键的元素列表。

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class Program
{
    class InvoiceProducts 
    {
        public int InvoiceID { get; set; }
        public int ProductID { get; set; }
    }

    public static void Main()
    {
         List<InvoiceProducts> list = new List<InvoiceProducts>();
        list.Add(new InvoiceProducts{ InvoiceID = 7000, ProductID=15});
        list.Add(new InvoiceProducts{ InvoiceID = 7000, ProductID=10});
        list.Add(new InvoiceProducts{ InvoiceID = 7000, ProductID=10});
        list.Add(new InvoiceProducts{ InvoiceID = 7000, ProductID=15});

        list.Add(new InvoiceProducts{ InvoiceID = 7010, ProductID=12});
        list.Add(new InvoiceProducts{ InvoiceID = 7010, ProductID=20});
        list.Add(new InvoiceProducts{ InvoiceID = 7010, ProductID=12});

        list.Add(new InvoiceProducts{ InvoiceID = 7021, ProductID=1});
        list.Add(new InvoiceProducts{ InvoiceID = 7021, ProductID=1});

        var lookup = list.Select(x => new { x.InvoiceID, x.ProductID })
                     .Distinct()
                     .ToLookup(x => x.InvoiceID, x => x.ProductID);

        foreach(var x in lookup)
        {
            Console.WriteLine(x.Key);
        }
    }
}

应该return：

7000 10,15
7010 12,20
7021 1

Answer 1

这应该有效：-

var result = list.GroupBy(x => x.InvoiceID)
                 .Select(x => x.Key + "," + 
                              String.Join(",", x.Select(z => z.ProductID).Distinct()));

Working Fiddle.

Answer 2

您只需要枚举 x 这是一个 IEnumerable<int>，您可以使用 String.Join 来连接所需的有序 int：

foreach(var x in lookup)
{
    Console.WriteLine("{0} {1}", x.Key, String.Join(",", x.OrderBy(i => i)));
}

您还可以创建一个集合，例如 List<int>:

foreach(var x in lookup)
{
    List<int> productList = x.ToList();
}

循环查找 - 将元素串在一起

Loop Lookup - string elements together

c#

linq

lookup

loops

element