Hi,

this works:

var q = (from c in metaData.FileTransferLog
         select c);
var list = new List<IO.Dailies.DailiesFileVersionDTO>();
foreach (var item in q)
{
    list.Add(CreateDailiesFileVersionDTO(item));
}

This throws the exception below when enumerating over the collection:

var t = (from c in metaData.FileTransferLog
         select CreateDailiesFileVersionDTO(c));

Any ideas why this might happen?

Thanks, Patrick

System.InvalidCastException was unhandled
  Message="Unable to cast object of type 'System.Int32' to type 'CFX.Amanda.DAL.EntityClasses.MyFileTransferLogEntity'."
  Source="Anonymously Hosted DynamicMethods Assembly"
  StackTrace:
       at lambda_method(ExecutionScope , Object[] , Int32[] )
       at SD.LLBLGen.Pro.LinqSupportClasses.DataProjectorToObjectList`1.AddRowToResults(IList projectors, Object[] rawProjectionResult)
       at SD.LLBLGen.Pro.LinqSupportClasses.DataProjectorToObjectList`1.SD.LLBLGen.Pro. ORMSupportClasses.IGeneralDataProjector.AddProjectionResultToContainer(List`1 valueProjectors, Object[] rawProjectionResult)
       at SD.LLBLGen.Pro.ORMSupportClasses.ProjectionUtils.FetchProjectionFromReader(List`1 valueProjectors, IGeneralDataProjector projector, IDataReader datasource, Int32 maxNumberOfItemsToReturn, Int32 pageNumber, Int32 pageSize, Boolean clientSideLimitation, Boolean clientSideDistinctFiltering, Boolean clientSidePaging, UniqueList`1 stringCache, Dictionary`2 typeConvertersToRun)
       at SD.LLBLGen.Pro.ORMSupportClasses.DataAccessAdapterBase.FetchProjection(List`1 valueProjectors, IGeneralDataProjector projector, IRetrievalQuery queryToExecute, Dictionary`2 typeConvertersToRun)
       at SD.LLBLGen.Pro.ORMSupportClasses.DataAccessAdapterBase.FetchProjection(List`1 valueProjectors, IGeneralDataProjector projector, IEntityFields2 fields, IRelationPredicateBucket filter, Int32 maxNumberOfItemsToReturn, ISortExpression sortClauses, IGroupByCollection groupByClause, Boolean allowDuplicates, Int32 pageNumber, Int32 pageSize)
       at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProvider2.ExecuteValueListProjection(QueryExpression toExecute)
       at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.ExecuteExpression(Expression handledExpression)
       at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.Execute(Expression expression)
       at SD.LLBLGen.Pro.LinqSupportClasses.LLBLGenProProviderBase.System.Linq.IQueryProvider.Execute[TResult](Expression expression)
       at System.Linq.Queryable.ElementAt[TSource](IQueryable`1 source, Int32 index)
  InnerException: 

I don't think the second approach would work, as "c" is not of MyFileTransferLogEntity type.

The reason is that 'c' isn't materialized into an entity when it is passed into the method call at runtime: entities are fetched using the entity fetch pipeline and not the projection pipeline to be able to use polymorphism during fetching.

You could create a different CTor in the DTO and pass all fields separately, that would work too.

Otis wrote:

You could create a different CTor in the DTO and pass all fields separately, that would work too.

Makes sense.

Thanks you, Patrick

If it's possible, I'd like a bit more explanation on this issue. I'm pretty sure I've been bitten by it multiple times in the last week on my project, but I've been chasing it around in weird directions.

Is this a bug in the Linq provider? Is this a bug in Linq?

The syntax seems valid, but it doesn't work.

            var results = from a in metadata.MyEntity
                        where a.Id == 1 
                        select new MyDTO(a);
            return results .Single();

But this works:

            var results = from a in metadata.MyEntity
                        where a.Id == 1 
                        select a;
            return new MyDTO(results .Single());

I'd like to understand it if it's a 'Train the Monkey' (me) issue. If it's not, is it possible to fix?

Thanks!

Hi Josh,

It's has been discussed a couple of times. Here are some links:

• User manual
• http://llblgen.com/TinyForum/Messages.aspx?ThreadID=15133&StartAtMessage=0&#84289
• http://llblgen.com/TinyForum/Messages.aspx?ThreadID=14390&StartAtMessage=0&#80241
• http://llblgen.com/TinyForum/Messages.aspx?ThreadID=13462&StartAtMessage=0&#74931