asp.net - 尝试通过 Linq to Entities 更新/插入多对多关系

Question

我正在尝试对多对多关系执行组合添加/更新功能。数据库优先。拥有三个sql表：Personnel、Orders、PersonnelOrders。这是我的代码：

context.ContextOptions.LazyLoadingEnabled = true;

if (saveData.Rows.Count() > 1)
                {
                    foreach (var row in saveData.Rows)
                    {
                        if (row != null)
                        {
                            var Order_Array = row.Order_Array; //Array of order id's to     be used below.


                            var pData = new Personnel;
                            {
                                Personnel_Id = row.Key,
                                Personnel_Name = row.Name                                
                            };

                            if (pData.Personnel_Id == 0) //ADD
                            {
                                foreach (int Id in Order_Array)
                                {
                                    pData.Orders.Add(new Order() { Order_Id = Id });
                                }

                                context.Personnel.AddObject(cvData);

                                foreach (var j in pData.Orders)
                                {
                                    context.ObjectStateManager.ChangeObjectState(j, EntityState.Unchanged);
                                }  
                            }
                            else  //Doesn't error out, but does not work either:
                            {
                                pData.Orders.Clear();
                                foreach (int Id in Order_Array)
                                {
                                       pData.Orders.Add(new Order() { Order_Id = Id });
                                }
                                context.Personnel.Attach(cvData);
                                context.ObjectStateManager.ChangeObjectState(pData, EntityState.Modified);
                            }

                            context.SaveChanges();


                        }
                    }
                }

                return "ok";

编辑：我让 ADD 工作，现在我被困在UPDATE上。请参阅上面的修改后的代码。

Answer 1

这是我必须做的才能让它工作。它对我来说看起来很丑，我相信它可以改进，但它现在有效。

context.ContextOptions.LazyLoadingEnabled = true;  //not sure that this is necessary

if (saveData.Rows.Count() > 1)
{
    foreach (var row in saveData.Rows)
    {
        if (row != null)
        {
            var Order_Array = row.Order_Array;

        if (row.Key == 0) //ADD
        {
            var pData = new Personnel;
            {
                Personnel_Id = row.Key,  //probably not needed but it doesn't break it
                Personnel_Name = row.Name                                
            };

            foreach (int Id in Order_Array)
            {
                var j = context.Orders.Where(c => c.Order_Id == Id).SingleOrDefault();
                pData.Orders.Add(j);
            }

            context.Personnel.AddObject(pData);

            foreach (var j in pData.Orders)
            {
                context.ObjectStateManager.ChangeObjectState(j, EntityState.Unchanged); //so that you don't actually add more orders
            }
        }
        else //UPDATE
        {
            var ap = context.Personnel.FirstOrDefault(x => x.Personnel_Id == row.Key);

            ap.Personnel_Name = row.Name;

            ap.Orders.Clear(); //clear out existing associations

            foreach (int Id in Order_Array)
            {
                var j = context.Orders.Where(c => c.Order_Id == Id).SingleOrDefault();
                ap.Orders.Add(j);  //rebuild new associations
            }
         }

         context.SaveChanges();
     }
   }
}