linq - 在 Linq 投影中设置 EntityCollection

Question

我想知道如何在 Linq 投影中设置 EntityCollection。下面是我的代码:

var orders = (from order in context.Orders
   select new
   {
    reference = order.reference,
    pe = order.OrderExecutions //this is an EntityCollection
   })
.AsEnumerable()
.Select(o =>
     (Orders)new Orders
     {
      reference = o.reference,
      OrderExecutions = o.pe
     }
).ToList().AsQueryable();

(这段代码看起来很奇怪，但它需要像这样才能在 telerik 网格中工作)

指令 OrderExecutions = o.pe 涉及此错误:

The EntityCollection has already been initialized. The InitializeRelatedCollection method should only be called to initialize a new EntityCollection during deserialization of an object graph.

OrderExecutions 是对象 Orders 中包含的 EntityCollection。

我怎样才能避免这个错误？有什么想法吗？

我是否应该修改 Order 对象中生成的代码？

[XmlIgnoreAttribute()]
[SoapIgnoreAttribute()]
[DataMemberAttribute()]
[EdmRelationshipNavigationPropertyAttribute("PModel", "FK__orderExec__refer__70DDC3D8", "OrderExecutions")]
public EntityCollection<OrderExecutions> OrderExecutions
{
 get
 {
  return ((IEntityWithRelationships)this).RelationshipManager.GetRelatedCollection<OrderExecutions>("PModel.FK__orderExec__refer__70DDC3D8", "OrderExecutions");
 }
 set
 {
  if ((value != null))
  {
   ((IEntityWithRelationships)this).RelationshipManager.InitializeRelatedCollection<OrderExecutions>("PModel.FK__orderExec__refer__70DDC3D8", "OrderExecutions", value);
  }
 }
}

提前谢谢你。

Answer 1

查询应该重写为

var orders = from order in context.Orders
             select new
             {
                 reference = order.reference,
                 OrderExecutions = order.OrderExecutions //this is an EntityCollection
              };

无需转换为 IEnumerable 然后重新选择相同的字段。然后不需要转换为 List，然后再转换回 IQueryable，因为 LINQ 查询自然会返回 IQueryable 对象。通过调用 ToList()，查询针对数据源执行。将这些电话推迟到任何其他限制实现后几乎总是更好。