使用LINQ从组列表中选择项目

Question

我有一个具有以下结构的模型；

{
   Name: // .... //,
   Id: // ... //,
   Tab: "tabName",
   // ... other properties ... //
}

是否可以采用此类型的IList<T>并通过Tab属性将项目提取到组中？ 这样我就可以仅使用LINQ查询得到这样的形状？

{
 "tabName1": [ item1, item4, item8 ],
 "tabName2": [ item2, item5, item9 ],
 "tabName3": [ item3, item6, item10]
}

Answer 1

我认为数据结构是这样的：

var obj = new[] { 
 new { Name = "ss", Id = 1, Tab = "tabName1" },
 new { Name = "ss", Id = 1, Tab = "tabName1" },
 new { Name = "ss", Id = 1, Tab = "tabName1" },
 new { Name = "ss", Id = 1, Tab = "tabName2" },
 new { Name = "ss", Id = 1, Tab = "tabName1" }
};

您可以通过以下方式使用组：

var query = from s in obj
            group s by s.Tab into newGroup
            select newGroup;

并使用方法语法：

var query = obj.GroupBy(p => p.Tab).Select(p => new { items = p });

Answer 2

您可以通过GroupBy方法执行此操作。 下面，我为您设置了一个演示。 该代码将产生一个列表。 该列表中的每个对象将具有一个键和一个items属性。 关键字将是标签名，而itemsproperty将包含一个包含项目的列表。

类

class TestObj
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Tab { get; set; }
}

例

List<TestObj> obj = new List<TestObj>()
{
     new TestObj() { Id = 1, Tab = "tab1", Name = "name1" },
     new TestObj() { Id = 2, Tab = "tab1", Name = "name2" },
     new TestObj() { Id = 3, Tab = "tab1", Name = "name3" },
     new TestObj() { Id = 4, Tab = "tab2", Name = "name4" },
     new TestObj() { Id = 5, Tab = "tab2", Name = "name5" },
     new TestObj() { Id = 6, Tab = "tab4", Name = "name6" },
     new TestObj() { Id = 7, Tab = "tab3", Name = "name7" },
     new TestObj() { Id = 8, Tab = "tab3", Name = "name8" },
     new TestObj() { Id = 9, Tab = "tab3", Name = "name9" },
 };

 var list = obj.GroupBy(x => x.Tab).Select(x => new { key = x.Key, items = x }).ToList();

Answer 3

试试这个

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Something> somethings = new List<Something>() {
                new Something() { tab = 1},
                new Something() { tab = 2},
                new Something() { tab = 3},
                new Something() { tab = 4},
                new Something() { tab = 5},
                new Something() { tab = 6},
                new Something() { tab = 7},
                new Something() { tab = 8},
                new Something() { tab = 9}
            };


            var result = somethings.Take(3).Select((x, i) => somethings.Where((y, ii) => (ii % 3) == i).Select(z => z.tab).ToArray()).ToArray();


        }
    }
    public class Something
    {
        public int tab { get; set; }
    }
}