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);更多推荐
ValueTuple.Create中的命名参数
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