Question

我需要一些帮助来过滤另一个对象列表中的对象列表。

当前，我能够过滤FirstLevel对象，使其仅返回与条件匹配的SecondLevel对象（列表中具有Id），如果碰巧具有ThirdLevel过滤器，则仅返回包含以下内容的SecondLevel对象：符合条件的ThirdLevel对象。

我需要的是ThirdLevel数组仅包含符合条件的数组。

我可以在单个Linq查询中做到这一点吗？

编辑：易于理解的（??）示例：假设我有一个壁橱，在这个壁橱中，我有很多抽屉。现在，在这些抽屉中，我有几双袜子，每双袜子的颜色都不同。我需要的是能够对抽屉进行过滤，以仅向我显示包含黑色袜子的那些，同时从抽屉中去除其他颜色。（不知道是否合理）

下面是示例代码：

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

namespace MyNamespace
{
    public class Program
    {
        public static void Main(string[] args)
        {
            List<int> filterSecondLevel = new List<int>(){1, 2};
            List<int> filterThirdLevel = new List<int>(){3};

            ThirdLevel _3a = new ThirdLevel(){Id=1};
            ThirdLevel _3b = new ThirdLevel(){Id=2};
            ThirdLevel _3c = new ThirdLevel(){Id=3};
            ThirdLevel _3d = new ThirdLevel(){Id=4};

            List<ThirdLevel> _3la = new List<ThirdLevel>(){_3a,_3b};
            List<ThirdLevel> _3lb = new List<ThirdLevel>(){_3c,_3d};

            SecondLevel _2a = new SecondLevel(){ Id=1, ThirdLevelList=_3la};
            SecondLevel _2b = new SecondLevel(){ Id=2, ThirdLevelList=_3lb};

            List<SecondLevel> _2la = new List<SecondLevel>(){_2a,_2b};

            FirstLevel _1a = new FirstLevel(){ Id=1, SecondLevelList=_2la};

            var result = _1a.SecondLevelList.Where(x => 
                                                          (filterSecondLevel.Count == 0 || filterSecondLevel.Contains(x.Id)) && 
                                                              x.ThirdLevelList.Where(y => 
                                                                  filterThirdLevel.Count == 0 || filterThirdLevel.Contains(y.Id)
                                                      ).ToList().Count > 0
                                                  ).ToList();
        }
    }

    public class FirstLevel
    {
        public int Id {get;set;}
        public List<SecondLevel> SecondLevelList { get; set; }
    }

    public class SecondLevel
    {
        public int Id {get;set;}
        public List<ThirdLevel> ThirdLevelList { get; set; }
    }

    public class ThirdLevel
    {
        public int Id {get;set;}
    }
}

Answer 1

您需要使用ANY（）

            var result = _1a.SecondLevelList.Where(x =>
                                                          (filterSecondLevel.Count == 0 || filterSecondLevel.Contains(x.Id)) &&
                                                              x.ThirdLevelList.Where(y => filterThirdLevel.Contains(y.Id)).Any())
                                                              .ToList();

如何过滤另一个列表中的对象列表

1 个答案: