FileHelpers Library - Append Multiple Records on Transform

Question

Using the FileHelpers library to do some great things in VB.NET. Parsing files with dynamic classes built from text file templates. One thing I can't find: A way to read in a single record and determine that it should result in the generation of two records.
Current Code:

Dim FromType As Type = Dynamic.ClassBuilder.ClassFromSourceFile(MyFilePath, MyDynamicTypeName, NetLanguage.VbNet)

Dim FromRecords() As Object FromRecords = FileHelpers.CommonEngine.ReadString(FromType, MyStringBuilder.ToString)

'... maybe code here to check for certain values

Dim engine As New FileTransformEngine(Of ITransformable(Of MyDestinationClass), MyDestinationClass)

' Ideally in this next line I would like it to see certain conditions and be able to generate two records from a single source line. Dim PayRecords() As Object = engine.TransformRecords(FromRecords)

Alternately, if there is a way to implement the "ITransformable(Of ..." TransformTo() and have it return multiple records, I could put the logic in the dynamic class definition TransformTo() method.

Thoughts?

Here is a sample of my source dynamic class:

Imports FileHelpers ' Never forget

_ Public NotInheritable Class MyDynamicClass Implements ITransformable(Of MyDestinationClass) _ Public Name As String

<FieldQuoted(""""c, QuoteMode.OptionalForRead, MultilineMode.AllowForRead)> _
Public KeyType As String

Public Hours As Double

Public Function TransformTo() As MyDestinationClass Implements ITransformable(Of MyDestinationClass).TransformTo Dim res As New MyDestinationClass

    res.ContactName = Name
    ' Here is where I would like to say... instead of Return res
    If KeyType="ABCD" Then
        Dim newRes as New MyDestinationClass
        newRes.Contactname = Name + " 2nd contact"

        Dim resArray() as MyDestinationClass
        redim resArray(1)
        resArray(0) = res
        resArray(1) = newRes
    End If
    Return resArray
    ' Or alternately refer to the engine, but it is not in scope for the dynamic record (is it?). Something like...
    engine.AppendToDestination(new MyDestinationClass(...))

End Function End Class

Answer 1

I think the main problem you're going to run into is that ITransformable.TransformTo() is spec'ed to return a single T value.

This is called in a loop when you call engine.TransformRecords(), where one output record is added for each input record.

I don't think this would be a big change if you didn't mind doing your own version of FileTransformEngine, but I don't see a clean way to do this as-is.