.Net - LINQ查询返回单个对象？

Question

是否可以使用LINQ查询返回单个对象而不是列表？

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

Answer 1

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,这将抛出异常.

如果你只想要第一个元素:

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

当没有元素存在时,使用SingleOrDefault()和FirstOrDefault()为引用类型返回null.