Question

我正在使用实体框架工作，并且我正在尝试加入。连接执行得很好，但是当我尝试循环结果时，我收到错误。见下文

 var items = from a in db.ActivityLogs
                            from v in db.Vehicles
                            where (a.PlateID1 == v.PlateID || a.PlateID2 == v.PlateID) && v.Alerted == true
                            select new { a, v };

执行正常，然后我收到错误

附加信息：无法投射类型＆＃39;＆lt;＆gt; f__AnonymousType0`2 [DB.ActivityLog，DB.Vehicle]＆＃39;输入＆＃39; DB.ActivityLog＆＃39;。

以下代码

foreach (ActivityLog l in items)

提前致谢

Answer 1

您已投射到匿名类型，因此无法将其投放到活动日志。

var items = (from a in db.ActivityLogs
                        from v in db.Vehicles
                        where (a.PlateID1 == v.PlateID || a.PlateID2 == 
                        v.PlateID) && v.Alerted == true
                        select new { a, v }).ToArray();

foreach (var item in items)
{
    Console.writeLine(item.a);
    Console.writeLine(item.v);

}

或

 var items = (from a in db.ActivityLogs
                        from v in db.Vehicles
                        where (a.PlateID1 == v.PlateID || a.PlateID2 == 
                        v.PlateID) && v.Alerted == true
                        select new ActivityLog
                        { 
                           A= a, // Pseudo code
                           V = v, // Pseudo code map to essential properties
                        }).ToArray();

foreach (ActivityLog l in items)

使用实体循环连接语句的resuts时出错

1 个答案: