LINQ：在和另一个列表中匹配任何名称（字符串）列表中返回的项目吗？ [英] LINQ: return items in a List that matches any Names (string) in another list?

问题描述

我有2列出。图1是产品的集合。另一种是产品在商店的集合。

我需要能够返回所有shopProducts如果名称中的产品匹配任何名称。

我有这个，但它似乎并没有工作。任何想法？

  VAR产品= shopProducts.Where（P =＆GT; p.Name.Any（listOfProducts。
             选择（L =＆GT; l.Name）。.ToList（）））了ToList（）;
 

我不吐不快其中名称中的其他列表中存在给我所有的shopproducts。

任何帮助真的AP preciated

感谢

解决方案

  VAR产品= shopProducts.Where（P =＆GT; listOfProducts.Any（L =＆GT; p.Name == l.Name））
                           .ToList（）;
 

有关LINQ到对象，如果 listOfProducts 包含很多项目，那么你的可能的，如果你创建一个 HashSet的＆LT; T＆GT; 包含所有需要的名，然后使用在您的查询。 的HashSet＆LT; T＆GT; 为O（1）查找性能相比O（n）的一个任意的IEnumerable＆LT; T＆GT;

  VAR名=新的HashSet＆LT;串GT;（listOfProducts.Select（P =＆GT; p.Name））;
变种产品= shopProducts.Where（P =＆GT; names.Contains（p.Name））
                           .ToList（）;
 

有关LINQ到SQL，我希望（希望？）的提供者可以自动优化生成的SQL而不需要查询的任何手动调整。

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

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

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();

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

Any help really appreciated

Thanks

解决方案

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

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();

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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