C# Linq to对象查询LLBLGen投影

我正在尝试使用推荐的LLBLGen语法来查询投影（）

我正在使用VS2010、.NET4和LLBLGEN2.6。 我想不出怎么解决这个问题有人能帮我一下吗

谢谢

编辑：

IEntityView2由LLBLGen生成，这是它的定义

public interface IEntityView2 : IEnumerable
{
    bool AllowEdit { get; set; }
    bool AllowNew { get; set; }
    bool AllowRemove { get; set; }
    int Count { get; }
    PostCollectionChangeAction DataChangeAction { get; set; }
    IPredicate Filter { get; set; }
    IEntityCollection2 RelatedCollection { get; }
    ISortExpression Sorter { get; set; }
    IEntity2 this[int index] { get; }
    event ListChangedEventHandler ListChanged;
    bool Contains(IEntity2 value);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, DataTable destination);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityCollection2 destination);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityDataProjector projector);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, DataTable destination, bool allowDuplicates);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityCollection2 destination, bool allowDuplicates);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityDataProjector projector, bool allowDuplicates);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, DataTable destination, bool allowDuplicates, IPredicate filter);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityCollection2 destination, bool allowDuplicates, IPredicate filter);
    void CreateProjection(List<IEntityPropertyProjector> propertyProjectors, IEntityDataProjector projector, bool allowDuplicates, IPredicate filter);
    int IndexOf(IEntity2 value);
    IEntityCollection2 ToEntityCollection();
    IEntityCollection2 ToEntityCollection(int startIndex);
}

公共接口IEntityView2:IEnumerable
{
布尔允许它{get；set；}
bool AllowNew{get；set；}
bool AllowRemove{get；set；}
整数计数{get；}
PostCollectionChangeAction数据更改操作{get；set；}
IPredicate筛选器{get；set；}
IEntityCollection2 RelatedCollection{get；}
ISortExpression分类器{get；set；}
IEntity2此[int索引]{get；}
事件ListChangedEventHandler ListChanged；
bool包含（IEntity2值）；
void CreateProjection（列出propertyProjectors、数据表目标）；
void CreateProjection（列出propertyProjectors、IEntityCollection2目标）；
void CreateProjection（列出propertyProjectors、IEntityDataProjector）；
void CreateProjection（列出propertyProjectors、DataTable destination、bool allowDuplicates）；
void CreateProjection（列出propertyProjectors、IEntityCollection2目标、bool allowDuplicates）；
void CreateProjection（列出propertyProjectors、IEntityDataProjector投影仪、bool allowDuplicates）；
void CreateProjection（列出propertyProjectors、DataTable destination、bool allowDuplicates、IPredicate筛选器）；
void CreateProjection（列出propertyProjectors、IEntityCollection2目标、bool allowDuplicates、IPredicate筛选器）；
void CreateProjection（列出propertyProjectors、IEntityDataProjector、bool allowDuplicates、IPredicate筛选器）；
int IndexOf（IEntity2值）；
EntityCollection 2到EntityCollection（）；
IENTITY集合2至实体集合（int startIndex）；
}

IEntityView2

继承非通用接口

IEnumerable

。但是，

Select

方法需要通用版本。这就是为什么会出现错误

假设要访问的属性是在

IEntity2

上定义的，则以下操作将起作用：

view.Cast<IEntity2>()
    .Select(c => new A1AllocationHelp1TableDTO
           {
               RecordStatus = c.RecordStatus,
               UniqueIdent = c.UniqueIdent
           })
    .ToList();

我使用的属性不存在（

IDontExist

）。此代码仍将编译，但在运行时引发异常：

MissingMemberException: Public member 'IDontExist' on type 'IEntity2' not found.
   at Microsoft.VisualBasic.CompilerServices.Symbols.Container.GetMembers(String& MemberName, Boolean ReportErrors)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.ObjectLateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) 

---

.DefaultView返回一个类型化视图，该视图实现了IEntityView2，但不应将其强制转换为IEntityView2，因为这样会丢失泛型类型。所以你应该这样做：

List<A1AllocationHelp1TableDTO> something = 
    (from c in table.DefaultView
     select new A1AllocationHelp1TableDTO
     {
         RecordStatus = c.RecordStatus,
         UniqueIdent = c.UniqueIdent
     }).ToList();

列出一些东西=
（来自table.DefaultView中的c）
选择新建A1AllocationHelp1TableDTO
{
RecordStatus=c.RecordStatus，
UniqueIdent=c.UniqueIdent
}).ToList（）；

---

这样，编译器就知道视图的泛型类型

请显示

IEntityView2

的定义。我已经编辑添加了cast实际要查看的定义。cast（）。选择（c=>…但这正是我想要的needed@kooshka：但是为什么要选择呢？如果

视图中的项已经是目标对象的项，则只需执行以下操作：
view.Cast（）.ToList（）；
。不需要创建新对象。我的不好。我的意思是Cast.view保存一个AllocationHelp1实体的实例，该实体仅在运行时定义，因为它在WCF中，所以我需要返回一个静态定义的DTOThanks Frans，但这也不起作用，我仍然会收到相同的错误。表的类型是IEntityCollection2
view.Cast<IEntity2>()
    .Select(c => new A1AllocationHelp1TableDTO
           {
               RecordStatus = c.RecordStatus,
               UniqueIdent = c.UniqueIdent
           })
    .ToList();

Dim view As IEntityView2 = table.DefaultView
Dim something As List(Of A1AllocationHelp1TableDTO) = _
(From c In view
 Select New A1AllocationHelp1TableDTO With _
      {
          .RecordStatus = c.IDontExist _
      }).ToList()

MissingMemberException: Public member 'IDontExist' on type 'IEntity2' not found.
   at Microsoft.VisualBasic.CompilerServices.Symbols.Container.GetMembers(String& MemberName, Boolean ReportErrors)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.ObjectLateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) 

List<A1AllocationHelp1TableDTO> something = 
    (from c in table.DefaultView
     select new A1AllocationHelp1TableDTO
     {
         RecordStatus = c.RecordStatus,
         UniqueIdent = c.UniqueIdent
     }).ToList();