.NET-LINQ查询返回单个对象? [英] .Net - LINQ query returning a single object?

问题描述

是否可以使用LINQ查询返回单个对象而不是列表?

Is it possible to use a LINQ query to return a single object instead of a list?

User user = (from User u in users 
     where u.id == 5
     select u);

推荐答案

是

User user = (from User u in users 
    where u.id == 5
    select u).Single()

如果查询返回多个元素，则将抛出异常.

This will throw and exception if more than one element is returned by the query.

如果只需要第一个元素:

If you only want the first element:

User user = (from User u in users 
    where u.id == 5
    select u).First()

在没有元素的情况下，使用SingleOrDefault()和FirstOrDefault()为引用类型返回null.

Use SingleOrDefault() and FirstOrDefault() to return null for reference types when no element exists.

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