Hi

I'm trying to create a simple custom operator to process the result of an outer join in GQI.

I basically want to use the value of the first column if not empty or the second column when the first column is empty.

I have this code, but it's difficult to debug where things go wrong in GQI:
using System;
using Skyline.DataMiner.Analytics.GenericInterface;
using Skyline.DataMiner.Net.Messages;

[GQIMetaData(Name = "Merge Outer Join Keys")] public class MergeOuterJoinKeys : IGQIColumnOperator, IGQIInputArguments
{
// Arguments
private readonly GQIColumnDropdownArgument _columnArg1;
private readonly GQIColumnDropdownArgument _columnArg2;
private readonly GQIStringArgument _newNameArg;

// Argument values
private GQIColumn _column1;
private GQIColumn _column2;

private string _newName;

// variables
private GQIColumn _mergedColumn;

public MergeOuterJoinKeys()
{
_columnArg1 = new GQIColumnDropdownArgument("Column 1") { IsRequired = true };
_columnArg2 = new GQIColumnDropdownArgument("Column 2") { IsRequired = true };
_newNameArg = new GQIStringArgument("Name of merged column") { IsRequired = true };
}

public GQIArgument[] GetInputArguments()
{
return new GQIArgument[] {
_columnArg1,
_columnArg2,
_newNameArg,
};
}

public OnArgumentsProcessedOutputArgs OnArgumentsProcessed(OnArgumentsProcessedInputArgs args)
{
_column1 = args.GetArgumentValue(_columnArg1);
_column2 = args.GetArgumentValue(_columnArg2);
_newName = args.GetArgumentValue(_newNameArg);

return default;
}

public void HandleColumns(GQIEditableHeader header)
{
_mergedColumn = new GQIStringColumn(_newName);
header.AddColumns(_mergedColumn);
}

public void HandleRow(GQIEditableRow row)
{

if (!row.TryGetValue(_column1, out string column1String))
{
throw new Exception("Column 1 not found");
}
if (!row.TryGetValue(_column2, out string column2String))
{
throw new Exception("Column 2 not found");
}

GenerateInformationEvent($"Column 1: {column1String}");
GenerateInformationEvent($"Column 2 {column2String}");

string mergedString;
if (column1String.Length > 0)
{
mergedString = column1String;
}
else
{
mergedString = column2String;
}

row.SetValue(_mergedColumn, mergedString);
}
}