LINQ 返回列表中与另一个列表中的任何名称(字符串)匹配的项目

问题描述

我有 2 个列表.1是产品的集合.另一个是商店中的产品集合.

I have 2 lists. 1 is a collection of products. And the other is a collection of products in a shop.

如果名称与产品中的任何名称匹配，我需要能够返回所有 shopProducts.

I need to be able to return all shopProducts if the names match any Names in the products.

我有这个，但它似乎不起作用.有什么想法吗?

I have this but it doesn't seem to work. Any ideas?

    var products = shopProducts.Where(p => p.Name.Any(listOfProducts.
             Select(l => l.Name).ToList())).ToList();

我需要说给我在另一个列表中存在名称的所有商店产品.

I need to say give me all the shopproducts where name exists in the other list.

推荐答案

var products = shopProducts.Where(p => listOfProducts.Any(l => p.Name == l.Name))
                           .ToList();

对于 LINQ-to-Objects，如果 listOfProducts 包含许多项目，那么如果您创建一个 HashSet，您可能会获得更好的性能包含所有必需的名称，然后在您的查询中使用它.HashSet 与任意 IEnumerable 的 O(n) 相比，具有 O(1) 的查找性能.

For LINQ-to-Objects, if listOfProducts contains many items then you might get better performance if you create a HashSet<T> containing all the required names and then use that in your query. HashSet<T> has O(1) lookup performance compared to O(n) for an arbitrary IEnumerable<T>.

var names = new HashSet<string>(listOfProducts.Select(p => p.Name));
var products = shopProducts.Where(p => names.Contains(p.Name))
                           .ToList();

对于 LINQ-to-SQL，我希望(希望?)提供程序可以自动优化生成的 SQL，而无需对查询进行任何手动调整.

For LINQ-to-SQL, I would expect (hope?) that the provider could optimise the generated SQL automatically without needing any manual tweaking of the query.

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