通过加入从另一个列表中填写属性

Question

我有两个模型：

public class Payment
{
  public Guid UserId {get;set;}
  public string UserName {get;set;}
  public string AddressLine1 {get;set;}
  public string AddressLine2 {get;set;}
  public decimal Amount{get;set;}
}

public class User
{
  public Guid Id {get;set;}
  public string Name {get;set;}
  public string PhoneNumber {get;set;}
}

在业务逻辑中，我正在做一些事情并接收两个对象：

list＆lt; user＆gt;用户和list＆lt;付款＆gt;付款。属性用户名 付款的一件事是空的，我需要通过加入两个列表（user.id == payment.userid）来填充它， 。

如何加入两个列表并接收列表＆lt;付款＆gt;付款带有填充<代码>用户名？

Answer 1

有很多方法可以使用：

解决方案1：付款 JOIN 用户。

payments = (from a in payments
join b in users on a.UserId equals b.Id
select new Payment
{
    UserId = a.UserId,
    UserName = b.Name,
    AddressLine1 = a.AddressLine1,
    AddressLine2 = a.AddressLine2,
    Amount = a.Amount
})
.ToList();

或

payments = payments.Join(users,
    payment => payment.UserId,
    user => user.Id,
    (payment, user) => new Payment 
    {
        UserId = payment.UserId,
        UserName = user.Name,
        AddressLine1 = payment.AddressLine1,
        AddressLine2 = payment.AddressLine2,
        Amount = payment.Amount
    }
);

解决方案2：迭代付款和查询用户。

using System.Linq;

foreach (var payment in payments)
{
    var user = users.Single(x => x.Id == payment.UserId);

    payment.UserName = user.Name;
}

Answer 2

使用以下方式：

var query = from payment in Payment
            join user in User
                 on payment.UserId equals user.Id
            select new
            {
             payment.UserId,
             payment.serName,
             payment.AddressLine1,
             payment.AddressLine2,
             payment.Amount,
             user.Name,
             user.PhoneNumber
            };