如果问题标题混乱,我很抱歉,我有一个场景,其中有两个用户类和地址。从另一个列表的ID获取列表中的项目
public class User
{
public int userId { get; set; }
public string userName { get; set; }
public List<Address> address { get; set; }
}
public class Address
{
public string AddressLine { get; set; }
public string City { get; set; }
public string State { get; set; }
public int UserId { get; set; }
}
UserId是类地址中的外键,我有两个List,用户列表和地址列表。用户地址的值为空,我想获得每个用户的地址列表,我如何实现这一点?我知道我们可以使用foreach,但有没有办法通过linq来实现这一点?以下是示例代码。
class Program
{
static void Main(string[] args)
{
var users = new List<User>();
users.Add(new User { userId = 1, userName = "User 1" });
users.Add(new User { userId = 2, userName = "User 2" });
users.Add(new User { userId = 3, userName = "User 3" });
users.Add(new User { userId = 4, userName = "User 4" });
var address = new List<Address>();
address.Add(new Address { AddressLine = "Address 1", City = "City 1", State = "State 1", UserId = 1 });
address.Add(new Address { AddressLine = "Address 1 Dup", City = "City 1", State = "State 1", UserId = 1 });
address.Add(new Address { AddressLine = "Address 2", City = "City 2", State = "State 2", UserId = 2 });
address.Add(new Address { AddressLine = "Address 2 Dup", City = "City 2", State = "State 2", UserId = 2 });
address.Add(new Address { AddressLine = "Address 3", City = "City 3", State = "State 3", UserId = 3 });
address.Add(new Address { AddressLine = "Address 3 Dup", City = "City 3", State = "State 3", UserId = 3 });
}
}
只是一个关于你的架构笔记...我会考虑是否有可能修改它。用地址存储用户ID是一个糟糕的设计。如果两个用户住在同一个地址,该怎么办?您应该真正拥有多对多的关系,即存储带有用户ID和地址ID的中间表。 –
这只是一个例子,因为我不能发布我的原代码。这将是安全漏洞,所以我很喜欢创建类似的虚拟数据。我同意这种模式设计是错误的。 –
LINQ也使用foreach。 [请点击此处](https://referencesource.microsoft.com/) – Badiparmagi