如何使用LINQ将两个不同结构的列表连接合并为指定结构的新列表

数据老陈

2026-10-2

实现方案

第一步：修正类定义语法错误

你提供的result类存在语法错误，修正后完整类定义如下：

public class list1
{
    public string ID { get; set; }
}

public class list2
{
    public string ID { get; set; }
    public string Member { get; set; }
}

public class result
{
    public string ID { get; set; }
    public List<list2> list2s { get; set; }
}

第二步：LINQ关联合并实现

以下两种实现方式均可满足需求，默认保留list1的所有元素，即使list2无对应匹配项也会生成list2s为空集合的result对象：

方式1：方法语法（GroupJoin）

直接调用LINQ原生GroupJoin方法实现关联分组：

// 模拟输入数据
List<list1> list1Data = new List<list1>
{
    new list1 { ID = "a" },
    new list1 { ID = "b" },
    new list1 { ID = "c" },
    new list1 { ID = "d" }
};
List<list2> list2Data = new List<list2>
{
    new list2 { ID = "a", Member = "1" },
    new list2 { ID = "a", Member = "2" },
    new list2 { ID = "a", Member = "3" },
    new list2 { ID = "b", Member = "1" },
    new list2 { ID = "b", Member = "2" },
    new list2 { ID = "c", Member = "1" },
    new list2 { ID = "d", Member = "1" }
};

// 核心关联逻辑
List<result> resultData = list1Data
    .GroupJoin(
        list2Data,
        l1 => l1.ID,
        l2 => l2.ID,
        (l1, l2Group) => new result
        {
            ID = l1.ID,
            list2s = l2Group.ToList()
        })
    .ToList();

方式2：查询语法

可读性更高的LINQ查询写法，逻辑和GroupJoin完全等价：

List<result> resultData = (
    from l1 in list1Data
    join l2 in list2Data on l1.ID equals l2.ID into l2Group
    select new result
    {
        ID = l1.ID,
        list2s = l2Group.ToList()
    }).ToList();