Problem with Image and varbinary fields

[bin]

Hi sir,
I am using the following code to return two fields from the table TestTable where the field FileContent datatype is Image or VarBinary .

var q = (from tt in objScope.Extent<TestTable>()
                  select new { tt.FileID, tt.FileContent }).ToList();

I got the following exception:-
System.InvalidCastException was unhandled
  Message=Object must implement IConvertible.
  Source=mscorlib
  StackTrace:
       at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
       at Telerik.OpenAccess.Query.NullableConverter`1.Convert(ResultData& data)
       at Telerik.OpenAccess.Query.ArrayConverter`1.Convert(ResultData& data)
       at Telerik.OpenAccess.Query.ObjectConstructor.Convert(ResultData& data)
       at Telerik.OpenAccess.Query.TypedEnumerator`1.ObtainCurrent()
       at Telerik.OpenAccess.Query.TypedEnumerator`1.System.Collections.Generic.IEnumerator<T>.get_Current()
     ... Local paths ...

       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at  ... Local paths ...
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

[Thomas]

Hello bin,

the issue has been fixed already, and the next build will contain the needed changes. As a workaround you can first do an empty projection, and then use the persistent field to perform the projection. 

All the best,
Thomas
the Telerik team

[bin]

Hello Sir,

What do you mean by " you can first do an empty projection, and then use the persistent field to perform the projection " ?
Could you please provide me with a code sample for the empty projection that handles my case.

Thanks

[Thomas]

Hi bin,

I meant

var q = (from tt in objScope.Extent<TestTable>()

         select tt).ToList().Select(xx => new { xx.FileID, xx.FileContent });

So, first perform no projection and thus get real persistent instances back, then use the instances to get the field value. Please make sure that the FileContent is
using the default fetch group too.

All the best,
Thomas
the Telerik team