Chaining InputOperations in Rhino-Etl - rhino-etl

Question

I've just recently started using Rhino-Etl for very simple ETL processes and have had great success with it. I have a slightly more complicated scenario to address now and I didn't find the ConventionInputCommandOperation behaving the way I expected.
I've done up a very simplified example of what I'm trying to do. Basically I have two systems involved and I don't know what I want to get from system 2 until I first query system 1. I thought registering an InputOperation immediately after another InputOperation would behave like a loop. So that each row in operation 1 would be fed to operation 2. The below code fails with "Failed to execute operation DetailReader: Must declare the scalar variable #PlanetAbbrv." So my question is how are you meant to handle situations where the input operation is dependent a previous input operation?
Thanks,
Brian
using System;
using Rhino.Etl.Core;
using Rhino.Etl.Core.ConventionOperations;
namespace ETLTest
{
class Program
{
static void Main()
{
new MainProcess().Execute();
Console.ReadLine();
}
}
public class MainProcess : EtlProcess
{
protected override void Initialize()
{
Register(new MainReader());
Register(new DetailReader());
}
protected override void PostProcessing()
{
foreach (var exception in GetAllErrors())
{
throw exception;
}
}
}
public class MainReader : ConventionInputCommandOperation
{
public MainReader() : base("Galactic1")
{
Command = #"select * from Planet";
}
}
public class DetailReader : ConventionInputCommandOperation
{
public DetailReader() : base("Galactic2")
{
Command = #"select * from Delivery where DeliveryPlanetAbbrv = #PlanetAbbrv";
}
}
}

Answer 1

You'll need to have your DetailReader select all rows (take out the where operation).
Then use a JoinOperation to match the details to the main information.
Register(new JoinPlanets()
.Right(new MainReader())
.Left(new DetailReader()));
public class JoinPlanets: JoinOperation
{
protected override Row MergeRows(Row leftRow, Row rightRow)
{
Row row = leftRow.Clone();
foreach (var column in leftRow.Columns)
row[column] = leftRow[column];
return row;
}
protected override void SetupJoinConditions()
{
FullOuterJoin.Left("PlanetAbbrv")
.Right("DeliveryPlanetAbbrv");
}
}