Question

我有以下两个POCO＆＃39>

public class Customers
{
    public Guid Id { get; set; }
    public string FirstName{ get; set; }
    public string LastName{ get; set; }
}

和

public class Orders
{
    public Guid Id { get; set; }
    public Guid CustomerId { get; set; }
    public string Product { get; set; }
    public DateTime Date { get; set; }
}

假设我的数据服务返回一个List＆lt; Customers＆gt;和列表＆lt;订单＆gt;，我如何使用Linq获得最有序的产品？

我想返回Order.Id，Order.Product和Count（作为控制器动作的Json），所以我还需要创建一个新的POCO来保存结果。如下所示：

public class CustomerOrders
{
    public Guid OrderId { get; set; }
    public string Product { get; set; }
    public int Count { get; set; }
}

Answer 1

一种方法是执行以下操作：

群组@set num1=1 :repeat @if %counter% == 500 exit @set /a num1= %num1% + 1 @SET /A a=%RANDOM% * 10 / 32768 + 1 @if %a% == 10 set life%num%=---- @if %a% == 9 set life%num%=O @if %a% == 8 set life%num%=^ @if %a% == 7 set life%num%=% @if %a% == 6 set life%num%=# @if %a% == 5 set life%num%=@ @if %a% == 4 set life%num%=) @if %a% == 3 set life%num%=() @if %a% == 2 set life%num%=~ @if %a% == 1 set life%num%=OO @echo %a% >>"gencode".txt @set /a num2= %num% + 1 @SET /A a=%RANDOM% * 10 / 32768 + 1 @if %a% == 10 set life%num%=---- @if %a% == 9 set life%num%=O @if %a% == 8 set life%num%=^ @if %a% == 7 set life%num%=% @if %a% == 6 set life%num%=# @if %a% == 5 set life%num%=@ @if %a% == 4 set life%num%=) @if %a% == 3 set life%num%=() @if %a% == 2 set life%num%=~ @if %a% == 1 set life%num%=OO @set final= 500 @set /a pass= %pass% + 1 @set /a cnum= %cnum% + 1 @set counterold=%counter% @set life%cnum%-%counter%= %a%-%b% @if %pass% == 1 goto start :repeat @if %ficnum% == 500 goto final @set life2%cnum%-%counter%= life%counterold%-life%counter% @set life2%cnum%-%counterold%= life%counterold%-life%counter% @set /a ficnum= %ficnum% + 1 @set life3%ficnum%-%counter%= life2%counterold%-life2%counter% @goto repeat :final @set /a final= %final% + 1 @set /a counter= %counter% + 1 @set /a ficnum= %ficnum% + 1 @set counter1= %counter% @set ficnum1= %ficnum% :finalst @set /a final= %final% - 1 @set /a counter1= %counter1% - 1 @set /a ficnum= %ficnum% - 1 @set /a ficnum1= %ficnum1% - 1 @set /a counter= %counter% - 1 @set final%final%=%life3%%ficnum%-%counter%-%life3%%ficnum1%-%counter1% @if %final% == 0 goto finalend @goto finalst :finalend @echo final0>"lifeform".txt
项目进入List<Order> by Product
按IEnumerable<CustomerOrders>

所以它看起来像这样：

Count

虽然(from o in orders group o by o.Product into og select new CustomerOrders { OrderId = og.First().Id, Product = og.First().Product, Count = og.Count() } ).OrderBy(r=>r.Count)没有多大意义，除非它是OrderId的列表，因为你想获得最有序的产品。

编辑：你是对的，这是正确的语法

Answer 2

试试这个。您不需要客户列表。

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Orders> orders = new List<Orders>();
            List<CustomerOrders> customerOrders = new List<CustomerOrders>();

            var productOrders = orders.AsEnumerable()
                .GroupBy(x => x.Product).ToList();

            foreach (var productOrder in productOrders)
            {
                CustomerOrders newOrder = new CustomerOrders();
                customerOrders.Add(newOrder);
                newOrder.OrderId = productOrder.FirstOrDefault().Id;
                newOrder.Product = productOrder.FirstOrDefault().Product;
                newOrder.Count = productOrder.Count();
            }

        }
    }

    public class Orders
    {
        public Guid Id { get; set; }
        public Guid CustomerId { get; set; }
        public string Product { get; set; }
        public DateTime Date { get; set; }
    }
    public class CustomerOrders
    {
        public Guid OrderId { get; set; }
        public string Product { get; set; }
        public int Count { get; set; }
    }
}

Answer 3

如果您更喜欢使用c＃语法而不是linq：

var groupedOrders = orders.GroupBy(o => o.Product);

这将返回每个组的IGrouping，其中key是产品名称，值是包含该产品的所有订单的IEnumerable

var sortedGroups = groupedOrders.OrderByDescending(g => g.Count());`

这会按照IEnumerable of orders

的计数对这些组进行排序

var projectedOrders = sortedGroups.Select(x => new CustomerOrders(){OrderId = x.First().Id, 
                                                  Product = x.First().Product, 
                                                  Count = x.Count()});

此处提供示例in angular2 http module

通过Linq的大多数订购产品

3 个答案: