LINQ的对象填充

Question

我希望更多地了解LINQ并使用它,所以在这里进行一些自我开发工作......

我有一个对象如下:

public class Player(){

    public string Name{get;set;}

    public Club currentClub{get;set;}

    public IEnumerable<Club> previousClubs{get;set;}

}

现在,给出一个球员名单,我想选择以前为各种俱乐部效力的球员,我可以通过嵌套的几个foreach声明轻松地做到这一点 - 但我想用Linq来做. .

我试过这个,但没有从中返回:

var prevClubs = 
    from player in players
    from clubOriginal in player.previousClubs
    from clubSecond in player.previousClubs
    from clubThird in player.previousClubs
    where clubOriginal.ID == 1
    where clubSecond.ID == 2
    where clubThird.ID == 3
    select new HistoryOfPlayer{ 
        firstClub == clubOriginal.Name,
        secondClub == clubSecond.Name,
        thirdClub == clubThird.Name
    }

我出错的地方有什么帮助吗？数据肯定是存在的,因为当我有一个环绕循环球员的环绕着球员的foreach循环并且我返回所有为俱乐部1,2和3效力的球员的集合有数据......

实际上它应该返回一个HistoryOfPlayer对象的几个实例,所有实例都包含相同3个俱乐部的名称(假设它们与ID相关联) - 正如我所说,它有点自学,所以试图将它应用于运动所以它我的脑袋里有点!!

有人可以帮忙吗？

Answer 1

你可以让它更有活力

List<int> clubIds = new List<int> { 1, 2, 3};
var prevClubs = from player in players
                where player.previousClubs.Any(m => clubIds.Contains(m.ID))
                select new HistoryOfPlayer {
                   Player = player, 
                   Clubs = player.previousClubs
                                 .Where(m => clubIds.Contains(m.ID))
                                 .Select(c => c.Name) 
                };

在 svik 之后编辑他的言论：

List<int> clubIds = new List<int> { 1, 2, 3};
var prevClubs = from player in players
                where clubIds.All(id => player.previousClubs
                                              .select(club => club.ID)
                                              .contains(id))
                select new HistoryOfPlayer {
                   Player = player, 
                   Clubs = player.previousClubs
                                 .Where(m => clubIds.Contains(m.ID))
                                 .Select(c => c.Name) 
                };

*注意这是在没有 IDE 的情况下编写的，所以我还没有检查它是否有效。