LINQ返回与另一个列表中的任何名称(字符串)匹配的列表中的项目 [英] LINQ return items in a List that matches any Names (string) in another list
问题描述
我有2个列表. 1是产品的集合.另一个是商店里的产品集合.
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();
我要说给我所有其他列表中存在名称的商店产品.
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,那么如果创建包含所有必需名称的HashSet<T>
并将其用于查询中,则可能会获得更好的性能.相对于任意IEnumerable<T>
的O(n),HashSet<T>
具有O(1)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(希望吗?)提供程序可以自动优化生成的SQL,而无需任何人工调整查询.
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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