在 LINQ to Entities 查询中无法构造实体或复杂类型“Mvc_MusicShop_diy.Models.Order”

 

错误代码：

var orders = db.Orders.Where(o => o.UserId == userid).Select(c =>

                 new Order

                 {

                     OrderId = c.OrderId,

                     OrderDate = c.OrderDate,

                     Total = c.Total,

                     OrderDetails = db.OrderDetailss.Where(od => od.OrderId == c.OrderId).ToList()

                 }

                 ).ToList();

正确代码：

var orders = db.Orders.Where(o=>o.UserId==userid).ToList().Select

               (c =>

              new Order

              {

                  OrderId = c.OrderId,

                  OrderDate = c.OrderDate,

                  Total = c.Total,

                  OrderDetails = db.OrderDetailss.Where(od => od.OrderId == c.OrderId).ToList()

              }

              ).ToList();

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原理： linq 选择数据时候 不能new 已知的对象，只能匿名的。 但是如果从一个 List 列表 就可以new 已知的类。