ValueTuple.Create中的命名参数

本文介绍了ValueTuple.Create中的命名参数的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我在C#中使用Value Tuple玩耍.

I was playing arround with the Value Tuple in C#.

首先提供一些演示数据:

First some demo data:

#region Data public class Product { public string Name { get; set; } public int CategoryID { get; set; } } public class Category { public string Name { get; set; } public int ID { get; set; } } public class Data { public List<Category> Categories { get; } = new List<Category>() { new Category(){Name="Beverages", ID=001}, new Category(){ Name="Condiments", ID=002}, }; public List<Product> Products { get; } = new List<Product>() { new Product{Name="Cola", CategoryID=001}, new Product{Name="Tea", CategoryID=001}, new Product{Name="Mustard", CategoryID=002}, new Product{Name="Pickles", CategoryID=002}, }; } #endregion

然后使用演示数据的方法:

Then a method using the demo data:

public static IEnumerable<(int CategoryId, string ProductName)> GetList() { var data = new Data(); return from category in data.Categories join prod in data.Products on category.ID equals prod.CategoryID select ValueTuple.Create(category.ID, prod.Name); }

到目前为止没有问题.

但是，如果我想要按产品名称排序的结果，可以执行以下操作:

But if I want a result sorted by Product name I can do as following :

public static IEnumerable<(int CategoryId, string ProductName)> GetList() { var data = new Data(); return (from category in data.Categories join prod in data.Products on category.ID equals prod.CategoryID select ValueTuple.Create(category.ID, prod.Name)).OrderBy(e => e.Item2); }

这是我的问题:使用ValueTuple.Create(...)时可以命名参数，因此可以在OrderBy中使用这些名称

And here I have my problem: when using ValueTuple.Create(...) can I name the parameters, so the names could be used in a OrderBy

我希望有这样的东西:

select ValueTuple.Create(CategoryId : category.ID, ProductName : prod.Name)

，然后在我的订单中使用该名称:

and then use the name in my orderBy:

OrderBy(e => e.ProductName)

推荐答案

您可以在 Select 中直接创建一个命名元组，并明确指出名称:

You can directly create a named tuple within your Select and explictly indicate the names:

( from category in data.Categories join prod in data.Products on category.ID equals prod.CategoryID select (CategoryId: category.Id, ProductName: prod.Name) ).OrderBy(e => e.ProductName);