C# 使用Linq根据属性对对象列表进行分组？

我有一个目标：

public class SiteInfo
        {
            public string Title { get; set; }
            public string URL { get; set; }
            public string Type { get; set; }     
        }

我正在使用它创建列表： var sites=新列表（）

---

然而，我想做的是在序列化之前按类型对站点进行分组。这是否可以使用LINQ或其他方法实现。

听起来您想要的是：

// No need to sort sites first
var grouped = sites.OrderBy(x => x.Type)
                   .GroupBy(x => x.Type);

var grouped = sites.OrderBy(x => x.Type)
                   .GroupBy(x => x.Type)
                   .Select(g => new { Type = g.Key,
                                      Sites = g.Select(site => new {
                                                           site.Title,
                                                           site.URL
                                                       } });

然后只需序列化

分组

。然而，我不知道在JSON中，

I分组

会是什么样子。。。每种情况下都会出现这种类型。您可能需要以下内容：

// No need to sort sites first
var grouped = sites.OrderBy(x => x.Type)
                   .GroupBy(x => x.Type);

var grouped = sites.OrderBy(x => x.Type)
                   .GroupBy(x => x.Type)
                   .Select(g => new { Type = g.Key,
                                      Sites = g.Select(site => new {
                                                           site.Title,
                                                           site.URL
                                                       } });

我想这会给你一个更好的JSON结构。

这个

var sites = new List<SiteInfo>()
{
    new SiteInfo(){Title="1",Type="a",URL="http://aaaa"},
    new SiteInfo(){Title="2",Type="b",URL="http://bbbb"},
    new SiteInfo(){Title="3",Type="a",URL="http://aaaa"},
    new SiteInfo(){Title="4",Type="b",URL="http://bbb"},
};

var json = new JavaScriptSerializer().Serialize(sites.GroupBy(s => s.Type));

或

var json = new JavaScriptSerializer().Serialize(sites.GroupBy(s => s.Type)
                                                      .ToDictionary(x=>x.Key,x=>x));

会产生

[
    [{"Title":"1","URL":"http://aaaa","Type":"a"},{"Title":"3","URL":"http://aaaa","Type":"a"}],
    [{"Title":"2","URL":"http://bbbb","Type":"b"},{"Title":"4","URL":"http://bbb","Type":"b"}]
]

{
    "a":[{"Title":"1","URL":"http://aaaa","Type":"a"},{"Title":"3","URL":"http://aaaa","Type":"a"}],
    "b":[{"Title":"2","URL":"http://bbbb","Type":"b"},{"Title":"4","URL":"http://bbb","Type":"b"}]
}

---

下面是一个简单的控制台应用程序，它可以满足您的需要：

static void Main(string[] args)
{
    List<SiteInfo> sites = new List<SiteInfo>()
    {
        new SiteInfo() { Title = "Site A", Type = "Whatever 2" },
        new SiteInfo() { Title = "Site B", Type = "Whatever 1" },
        new SiteInfo() { Title = "Site C", Type = "Whatever 1" },
        new SiteInfo() { Title = "Site D", Type = "Whatever 3" },
        new SiteInfo() { Title = "Site E", Type = "Whatever 3" }
    };

    var sitesGroupedByType =
        sites.GroupBy(s => s.Type).Select(g => new { Type = g.Key,
                                    Sites = g.Select(site => new
                                    {
                                          site.Title,
                                          site.URL
                                    })});

    foreach (var siteTypeGroup in sitesGroupedByType.OrderBy(g => g.Type))
    {
        foreach(var site in siteTypeGroup.Sites)
        {
            Console.WriteLine(string.Format("Type => {0}, Title => {1}",
                              siteTypeGroup.Type, site.Title));
        }
    }

    Console.ReadKey();
}

---

首先，我将查看所有LINQ方法的列表，并查看其中是否有与分组功能相关的方法。如果你这样做，

GroupBy

将有望脱颖而出-1明确表示没有投入任何研究工作。