NET9 Alpha - LINQ更新

在最新的 .NET 9 Alpha 版本中,LINQ(语言集成查询)引入了新方法,增强了数据操作的简单性和可读性。这些方法为常见任务提供了一种更直观的方法,例如根据特定键对元素进行计数和聚合,从而降低了复杂性

.NET9 Before

.NET9之前操作如下代码,较多。

using System;using System.Collections.Generic;using System.Linq;
class Program{    static void Main()    {        // Define a list of users        var users = new List        {            new User { Name = "Alice", Role = "Admin" },            new User { Name = "Bob", Role = "Member" },            new User { Name = "Charlie", Role = "Admin" },            new User { Name = "David", Role = "Member" },            new User { Name = "Eve", Role = "Guest" },            new User { Name = "Frank", Role = "Admin" }        };
        // CountBy Role using GroupBy and Select        var roleCounts = users            .GroupBy(user => user.Role) // Group users by their roles            .Select(group => new { Role = group.Key, Count = group.Count() }); // Select the role and count for each group
        // Print the results        foreach (var roleCount in roleCounts)        {            Console.WriteLine($"Role: {roleCount.Role}, Count: {roleCount.Count}");        }    }}
// User class definitionpublic class User{    public string Name { get; set; }    public string Role { get; set; }    // Add more properties if needed}

.NET9 after

随着 .NET 9 的引入,可以使用更简洁、更直观的代码实现相同的操作。通过在内部处理分组和计数来简化过程,直接返回一个集合,其中键是组,值是该组中元素的计数​​​​​​​

foreach (var roleCount in users.CountBy(user => user.Role)){    Console.WriteLine($"There are {roleCount.Value} users with the role {roleCount.Key}");}

输出:​​​​​​​

There are 3 users with the role AdminThere are 2 users with the role MemberThere are 1 users with the role Guest

虽然 LINQ 方法的第三方库提供了一些扩展功能,但这些方法正式包含在 .NET 9 Alpha 版本中标志着一个重要的里程碑。它标志着 Microsoft 致力于增强 LINQ 库本身,将这些强大且急需的功能直接集成到核心框架中,确保直接来自 .NET 生态系统的主要维护者的强大支持和优化

你可能感兴趣的:(linq,c#)