Question

我想要在Linq中分组一组对象。但是我想要使用的密钥是多个密钥的组合。例如

Object1: Key=SomeKeyString1

Object2: Key=SomeKeyString2

Object3: Key=SomeKeyString1,SomeKeyString2

现在我希望结果只有两组

Grouping1: Key=SomeKeyString1 : Objet1, Object3

Grouping2: Key=SomeKeyString2 : Object2, Object3

基本上我希望同一个对象成为两个组的一部分。 Linq有可能吗？

Answer 1

嗯，不是直接 GroupBy或GroupJoin。这两个都从对象中提取单个分组键。但是，您可以执行以下操作：

from groupingKey in groupingKeys
from item in items
where item.Keys.Contains(groupingKey)
group item by groupingKey;

示例代码：

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

class Item
{
    // Don't make fields public normally!
    public readonly List<string> Keys = new List<string>();
    public string Name { get; set; }
}

class Test
{
    static void Main()
    {
        var groupingKeys = new List<string> { "Key1", "Key2" };
        var items = new List<Item>
        {
            new Item { Name="Object1", Keys = { "Key1" } },
            new Item { Name="Object2", Keys = { "Key2" } },
            new Item { Name="Object3", Keys = { "Key1", "Key2" } },
        };

        var query = from groupingKey in groupingKeys
                    from item in items
                    where item.Keys.Contains(groupingKey)
                    group item by groupingKey;

        foreach (var group in query)
        {
            Console.WriteLine("Key: {0}", group.Key);
            foreach (var item in group)
            {
                Console.WriteLine("  {0}", item.Name);
            }
        }
    }
}

我可以在LINQ中向多个组添加相同的对象吗？

1 个答案: