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Is it possibale to cast a entity into a interface with a linq Query

Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2010
Forum Discription: For .NET 4.0
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=2925
Printed Date: 13-May-2026 at 9:25pm


Topic: Is it possibale to cast a entity into a interface with a linq Query
Posted By: JJANSSEN
Subject: Is it possibale to cast a entity into a interface with a linq Query
Date 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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Replies: 
      

      Posted By: sbelini
      

      Date 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<ICustomer> back to the client, and the 
serializer doesn't know what a List<ICustomer> 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.


         		
        

       

       

      

      
      Posted By: JJANSSEN
      

      Date 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.



         		
        

       

       

      

      
      Posted By: JJANSSEN
      

      Date 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



         		
        

       

       

      

      
    		
  








  

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