Hello

I have a question about “Polymorphic Prefetch Paths,” I am using adapter setup, and I have read the little entry on the manual about this.

Here is my database lay out

PointIndex -> (key)PointType -> (key)Protocol -> (key)ProtocolSettingGroupInfo.

I am trying from a record from PointIndex to read a text entry related to that record on ProtocolSettingGroupInfo.

I am using the following code:

EntityCollection pointIndexCollection = new EntityCollection(new PointIndexEntityFactory());

IPrefetchPath2 prefetchPath = new PrefetchPath2((int)EntityType.PointIndexEntity);
prefetchPath.Add(ProtocolEntity.PrefetchPathProtocolSettingGroupInfo);


RelationPredicateBucket bucket = new RelationPredicateBucket();

IPredicateExpression filter = new PredicateExpression();
filter.Add(PredicateFactory.CompareValue(PointIndexFieldIndex.PointIndexID,ComparisonOperator.Equal,0));

bucket.PredicateExpression.Add(filter);

int returnRecords = 0;

using (DataAccessAdapter dataAccessAdapter = new DataAccessAdapter(ConnectionString.GetZoneServer()))
{
    try
    {
        dataAccessAdapter.FetchEntityCollection(pointIndexCollection, bucket, prefetchPath);
        returnRecords = pointIndexCollection.Count;
    }
    catch(Exception e)
    {
        Console.WriteLine(e.ToString());
    }
}

And I get the following error when trying to run it: System.ApplicationException: The prefetch path element at index 0 in the passed in prefetch path for root entity type 12 is meant for root entity type 23 which isn't a subtype of 12 at SD.LLBLGen.Pro.ORMSupportClasses.DataAccessAdapterBase.FetchParameterisedPrefetchPath(IEntityCollection2 rootEntities, Int64 maxNumberOfItemsToReturn, IPrefetchPath2 prefetchPath) at SD.LLBLGen.Pro.ORMSupportClasses.DataAccessAdapterBase.FetchPrefetchPath(IEntityCollection2 rootEntities, IRelationPredicateBucket filterBucket, Int64 max NumberOfItemsToReturn, ISortExpression sortClauses, IPrefetchPath2 prefetchPath) at SD.LLBLGen.Pro.ORMSupportClasses.DataAccessAdapterBase.FetchEntityCollection(IEntityCollection2 collectionToFill, IRelationPredicateBucket filterBucket, IPrefetchPath2 prefetchPath) at InformationIntellect.DVM.ZoneServer.CO.Debug.TerminalTest.Main(String[] args) in C:\InformationIntellect\DVM\ZoneServer\CO.Debug\TerminalTest.cs:line 52

Could someone please point me in the right direction?

Thank you, BrunoV

You should start the prefetchPath from the entity you are fetching and move along the chain using SubPaths till you reach your final entity.

IPrefetchPath2 prefetchPath = new PrefetchPath2((int)EntityType.PointIndexEntity);
prefetchPath.Add(PointIndexEntity.PrefetchPathPointType).SubPath.Add( PointTypeEntity.PrefetchPathProtocol).SubPath.Add(ProtocolEntity.PrefetchPathProtocolSettingGroupInfo);

It worked

Thank you very much Walaa.

I knew I was just missing a piece of fundamental information.