DevForce Community Forum : Is it possibale to cast a entity into a interface with a linq Query

Is it possibale to cast a entity into a interface with a linq Query : I found a solution in collaboration...

Tue, 30 Aug 2011 03:36:56 -700

Author: JJANSSEN
Subject: 2925
Posted: 30-Aug-2011 at 3:36am

I found a solution in collaboration with Marcel Good:

public INotifyCompleted LoadHierarchieStruktur(Action<IEnumerable<IHierarchieElement>> onSuccess, Action<Exception> onFail){                        ITypedEntityQuery baseQuery  = Manager.Sortiment.Include("UnterSortimente");             var predicate = PredicateBuilder.Make("Ebene", FilterOperator.IsEqualTo, "1");            var op = baseQuery.Where(predicate).ExecuteAsync();            return op.OnComplete(result => { if (onSuccess != null) onSuccess(result.Cast<IHierarchieElement>()); }, onFail);            }


An approach for the solution was found in the documentation section.
http://drc.ideablade.com/xwiki/bin/view/Documentation/predicatebuilder-methods

Regards, Johannes

Is it possibale to cast a entity into a interface with a linq Query : Hi Silvio,we have an GUI-Componten...

Fri, 26 Aug 2011 00:22:27 -700

Author: JJANSSEN
Subject: 2925
Posted: 26-Aug-2011 at 12:22am

Hi Silvio,

we have an GUI-Componten to display Data in a TreeView. The general Component did not know which Entity are inside in the model but know the entity has the Interface like "IHierarchieElement" with the methode "GetName(), GetNumber()".

We have an idea to find a solution, while we transfor the entity in the GUI into another objekt with the interface "IHierarchieElement". A disadvantage is that it is complex and more code.

Regards,

Johannes.

Is it possibale to cast a entity into a interface with a linq Query : Hi Jjanssen,Unfortunatelly...

Thu, 25 Aug 2011 17:05:22 -700

Author: sbelini
Subject: 2925
Posted: 25-Aug-2011 at 5:05pm

Hi Jjanssen,

Unfortunatelly this will not be possible.

The issue is that the DF don't have enough information to serialize the results back to the client for non-scalar query results.

It will try to send a List back to the client, and the serializer doesn't know what a List is.

So the list form of the query will always fail, for any entity type.

Can you elaborate on why you are trying this approach, so I can better understand and assist?

Regards,

Silvio.

Is it possibale to cast a entity into a interface with a linq Query : Header ofthe partial class ...

Thu, 25 Aug 2011 09:06:17 -700

Author: JJANSSEN
Subject: 2925
Posted: 25-Aug-2011 at 9:06am

Header of the partial class

public partial class Sortiment : IbEm.Entity , IHierarchieElement

Methode to invoke a query with Linq and Cast it.

 public INotifyCompleted LoadHierarchieStruktur(Action<IEnumerable<IHierarchieElement>> onSuccess, Action<Exception> onFail)        {            EntityQueryOperation<IHierarchieElement> op = Manager.Sortiment.Cast<IHierarchieElement>()                .Where(c => c.GetEbene().Equals("1"))                .ExecuteAsync();             return op.OnComplete(onSuccess, onFail); }

I ask because we get an exception:

Unable to locate type: System.Linq.IQueryable`1[[~.IHierarchieElement, Common.SL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e. Check that the assembly holding this type is available in the bin/exe folder. Also check that both your assemblies and DevForce assemblies have the expected version number on both client and server.

We checked assemblies and do not find the solution :-(.

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