Linq 按列表列表分组并从两个列表中进行选择

Question

因此，我目前在为 Linq 处理 Group By 时遇到了麻烦，本质上我希望从 Pirate 中获取 id 以及 Ships 中的所有信息，理想情况下将其放入 IEnumerable DataRow 列表中（DataRow 被隐藏了......） .

public class Pirate
    {
        public string Id { get; set; }
        public List<Ship> Ships { get; set; }
    }
    public class Ship
    {
        public string Name { get; set; }
        public string ShipClass { get; set; }
        public string AvastyMast { get; set; }
    }

static void Main(string[] args)
    {
        List<Pirate> Pirates = new List<Program.Pirate>();

        Pirate Arr = new Pirate();
        Arr.Id = "1";

        Ship Pinta = new Ship();
        Pinta.Name = "Maria";
        Pinta.ShipClass = "BattleShip";
        Pinta.AvastyMast = "You Sunk My BattleShip";

        Ship Manta = new Ship();
        Pinta.Name = "Clara";
        Pinta.ShipClass = "Scout";
        Pinta.AvastyMast = "You Sunk My BattleShip!";

        Arr.Ships.Add(Pinta);
        Arr.Ships.Add(Manta);

        Pirates.Add(Arr);

        Pirate Sid = new Pirate();
        Sid.Id = "2";

        Ship Nuclara = new Ship();
        Pinta.Name = "Boon";
        Pinta.ShipClass = "Sub";
        Pinta.AvastyMast = "You Sunk My BattleShip!!";

        Ship Nutella = new Ship();
        Pinta.Name = "Slimer";
        Pinta.ShipClass = "Scout";
        Pinta.AvastyMast = "You Sunk My BattleShip!!!";


    }

所以我想做的是通过上面的 Linq 获得一个 DataRows 列表，这样如果我遍历每个 DataRow 并写出每一行和每一列，它将产生以下内容。

1 , Maria, BattleShip, You Sunk My Battleship
1 , Clara, Scout, You Sunk My Battleship!
2 , Boon, Sub, You Sunk My Battleship!!
2, Slimer, Scout, You Sunk My Battleship!!!

Answer 1

你可以试试这个：

var pirates = new List<Pirate>(); // or wherever your pirates will come from

var data = from p in pirates
           let pirateId = p.Id
           from s in p.Ships
           select new
           {
               PirateId = pirateId,
               Name = s.Name,
               Class = s.ShipClass,
               AvastyMast = s.AvastyMast
           };

如果你真的想从中取出DataRow 对象，你可以创建一个小方法来创建DataRow：

private static DataRow CreateDataRow(DataTable table, string pirateId, string name,
    string shipClass, string avastyMast)
{
    var row = table.NewRow();

    // Make sure the column names match those in the table!
    row["PirateId"] = pirateId;
    row["Name"] = name;
    row["ShipClass"] = shipClass;
    row["AvastyMast"] = avastyMast;

    return row;
}

并像这样使用它：

var pirates = new List<Pirate>(); // or wherever your pirates will come from
var dataTable = new DataTable(); // or wherever your DataTable will come from

var data = from p in pirates
           let pirateId = p.Id
           from s in p.Ships
           select CreateDataRow(dataTable , pirateId, s.Name, s.ShipClass, s.AvastyMast);

Answer 2

试试这个

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Pirate> pirates = new List<Pirate>() {
                    new Pirate() { id = "1" , Ships = new List<Ship>(){
                        new Ship() { name = "Maria", _class = "BattleShip", avastyemast = "You Sunk My Battleship"},
                        new Ship() { name = "Clara", _class = "Scout", avastyemast = "You Sunk My Battleship"}
                    }
                },
                    new Pirate() { id = "2" , Ships =  new List<Ship>() {
                        new Ship() { name = "Boon", _class = "Sub", avastyemast = "You Sunk My Battleship"},
                        new Ship() { name = "Slimer", _class = "Scout", avastyemast = "You Sunk My Battleship"}
                    }
                }
            };

            DataTable dt = new DataTable();
            dt.Columns.Add("id", typeof(string));
            dt.Columns.Add("name", typeof(string));
            dt.Columns.Add("class", typeof(string));
            dt.Columns.Add("avastyemast", typeof(string));

            foreach (Pirate pirate in pirates)
            {
                foreach(Ship ship in pirate.Ships)
                {
                    dt.Rows.Add(new string[] {
                        pirate.id,
                        ship.name,
                        ship._class,
                        ship.avastyemast
                    });
                }

            }


            //using linq
           var newRows = pirates.Select(x => x.Ships.Select(y => new List<object>() {x.id, y.name, y._class, y.avastyemast})).SelectMany(z => z).ToList();
           foreach (var row in newRows)
           {
               dt.Rows.Add(row);
           }
        }
    }
    public class Pirate
    {
        public string id {get;set;} 
        public List<Ship> Ships {get;set;}

    }
    public class Ship
    {
        public string name {get;set;}
        public string _class {get;set;}
        public string avastyemast {get;set;}
    }
}
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