C# EF can'；获取实体的导航属性的引用实体

这是我的模型课

public class Serve
{
    public int Id { get; set; }
    public Table Table { get; set; }
    public bool IsFinished { get; set; }
    public decimal TotalMoney { get; set; }
    public virtual ICollection<Order> Orders { get; set; }
}
public class Order
{
    public int Id { get; set; }
    public Item Item { get; set; }
    public int Numbers { get; set; }
    public bool IsCheifReceived { get; set; }
    public bool IsCheifCooked { get; set; }
    public Serve Serve { get; set; }

    public Order()
    {
        IsCheifCooked = IsCheifReceived = false;
    }
}

public class Item
{
    public int Id { get; set; }    
    public string Name { get; set; }    
    public string Unit { get; set; }
    public decimal Price { get; set; }    
    public Category Category { get; set; }    
    public bool IsNeedToNotifyChief { get; set; }
}

但是在本例中，在

.GroupBy（m=>m.Item）

中

m.Item

为

null

，它将所有订单分组到一个组中。（我知道问题是

m.Item

未加载到此查询中）

在这里，我不知道如何使m.Item加载到这个LINQ查询中。 请帮我做这个

---

注意：我使用实体框架6，我认为变量服务的是一些对象的列表，而不是查询。如果我是对的，当您从DB获得服务时，您应该包括项目。它看起来像下面的代码：

var serving = db.Serves
                 .Include(x => x.Orders)
                 .Include(x => x.Orders.Select(x => x.Item)) //here you'll get your items
                 .Where(m => m.Table.Id == ta && m.IsFinished == false)
                 .OrderByDescending(m => m.Id)
                 .FirstOfDefault();

//and after that your code should work correctly

if(serving != null) //don't forget check it, if you use FirstOfDefault()
{
   var groupedOrder = serving.Orders
            .OrderByDescending(m => m.Id)
            .GroupBy(m => m.Item) 
            .Select(g => new
            {
                Item = g.Key,
                Numbers = g.Sum(ri => ri.Numbers)
            }).ToList();
}

---

上面提到的

服务

类的对象。您在哪里初始化

订单

？@X-TECH我问的不是类

服务

，我问的是

服务

variable@Back我说,，这是服务的

对象

，我不知道他在哪里初始化它。右键点击“服务”->“转到定义”将帮助您找到它

var serving = db.Serves
                 .Include(x => x.Orders)
                 .Include(x => x.Orders.Select(x => x.Item)) //here you'll get your items
                 .Where(m => m.Table.Id == ta && m.IsFinished == false)
                 .OrderByDescending(m => m.Id)
                 .FirstOfDefault();

//and after that your code should work correctly

if(serving != null) //don't forget check it, if you use FirstOfDefault()
{
   var groupedOrder = serving.Orders
            .OrderByDescending(m => m.Id)
            .GroupBy(m => m.Item) 
            .Select(g => new
            {
                Item = g.Key,
                Numbers = g.Sum(ri => ri.Numbers)
            }).ToList();
}