Question

你有3个模型列表，它们包含奇数个元素，它们都是由userId加入的。

现实世界中的这3个模型列表将在执行时从3个存储过程中获取数据。我正在尝试使用Linq来对外加入他们，＆＃34;我不知道怎么做＆＃34;。我知道在Linq中有一个左连接但是说如果出现第一个列表被填充的情况，然后在第二个和/或第三个列表被填充之前，新用户被添加了所有3个表的相关数据。因此，新用户数据将位于第二个和第三个表上，而不是第一个表我希望在将它们与Linq一起收集之后，我的ViewModel会显示所有数据吗？这是当您需要右连接时，因为您希望在左表数据上显示空值。

有人知道是否有办法为此进行正确的加入，还是有更好的方法？下面是3对象列表，我需要将它们用于使用Linq为我的Viewmodel收集。

请提出建议。

B

class Program
{
    static void Main(string[] args)
    {
        List<CommissionBrokerReport> dailyReports = new List<CommissionBrokerReport>(new CommissionBrokerReport[]
        { 
            new CommissionBrokerReport { userId  = 101, firstName = "Bruce", lastName = "Wayne", value = 17433.3333M, average = 0M },
            new CommissionBrokerReport { userId  = 303, firstName = "Selina", lastName = "Kyle", value = 7279.13M, average = 0M }
        });
        List<CommissionBrokerReport> weeklyReports = new List<CommissionBrokerReport>(new CommissionBrokerReport[]
        { 
            new CommissionBrokerReport { userId  = 101, value = 0M, average = 7532.9167M },
            new CommissionBrokerReport { userId  =303, value = 0M, average = 0M },
            new CommissionBrokerReport { userId  = 404, value = 33.3333M, average = 666.6666M }
        });
        List<CommissionBrokerReport> monthlyReports = new List<CommissionBrokerReport>(new CommissionBrokerReport[]
        { 
            new CommissionBrokerReport { userId  = 101, value = 37550.0000M, average = 4653.7500M },
            new CommissionBrokerReport { userId  = 303, value = 0M,  average = 0M },
            new CommissionBrokerReport  { userId  = 404, value = 33.3333M, average = 666.6666M },
            new CommissionBrokerReport  { userId  = 505, value = 55.5555M, average = 10000.0000M }
        });
    }
}

Answer 1

这是join 3 list的一种方式，可以获取null来自不同list的丢失记录的结果。

var MonthlyWeeklyRpt = 
  from m in monthlyReports
  join w in weeklyReports on m.userId equals w.userId into weeklyrpt
  from w in weeklyrpt.DefaultIfEmpty()
  select new
  {
     MonthlyReports = m,
     WeeklyReports = w
  };


var MonthlyWeeklyDailyRpt = 
 from q in MonthlyWeeklyRpt
 join d in dailyReports on q.MonthlyReports.userId equals d.userId into dailyrpt
 from d in dailyrpt.DefaultIfEmpty()
 select new
 {
   MonthlyReports = q.MonthlyReports,
   WeeklyReports = q.WeeklyReports,
   DailyReports =d
 };

        foreach (var item in MonthlyWeeklyDailyRpt)
        {
            Console.WriteLine("monthly reports");
            Console.WriteLine(item.MonthlyReports.userId + " " + item.MonthlyReports.value);


            if (item.WeeklyReports != null)
            {
                Console.WriteLine("weekly reports");
                Console.WriteLine(item.WeeklyReports.userId + " " + item.WeeklyReports.value);                   
            }
            else
                Console.WriteLine("null weekly report");


            if (item.DailyReports != null)
            {
                Console.WriteLine("daily reports");
                Console.WriteLine(item.DailyReports.userId + " " + item.DailyReports.value);

            }
            else
                Console.WriteLine("null daily report");

            Console.WriteLine(" ");

        }

它将打印以下输出

monthly reports
101 37550.0000
weekly reports
101 0
daily reports
101 17433.3333

monthly reports
303 0
weekly reports
303 0
daily reports
303 7279.13

monthly reports
404 33.3333
weekly reports
404 33.3333
null daily report

monthly reports
505 55.5555
null weekly report
null daily report

我希望它会帮助你。

Linq右边加入3个奇怪的对象集合

1 个答案: