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
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.