QueryResults Constructor confusion

Ignition
1

Hello!

I'm a bit confused about the following constructor form of QueryResults:
QueryResults(Dataset dataset, QueryResults parent, int parentRow)

What is the purpose of the parent and parentRow params?

I thought that maybe they were required when using addNestedQueryResults, however from my very basic testing It seems like they are not needed (parent) nor used (parentRow) ??

example: In the reporting module I created the following Script data source examples:

ParentA: Here I'm passing in the nested child query results in a different order to their constructed parentRow param, and looking at the preview the parentRow param did not seem to make any affect to the order the nested queries were attached.

ParentB: Here I'm not even bothering with specifying a parent or parentRow, and it doesn't seem to cause any problems either with the preview results.

def updateData(data, sample):
	from system.report import QueryResults
	DataSet = system.dataset.toDataSet
	
	parent_qr_a = QueryResults(DataSet(["Row"],[[0],[1]]))
	child_qr_a_0 = QueryResults(DataSet(["Child_0"],[["value_0"]]), parent_qr_a, 0)
	child_qr_a_1 = QueryResults(DataSet(["Child_1"],[["value_1"]]), parent_qr_a, 1)
	parent_qr_a.addNestedQueryResults("Child",[child_qr_a_1, child_qr_a_0])
	data["ParentA"] = parent_qr_a
	
	parent_qr_b = QueryResults(DataSet(["Row"],[[0],[1]]))
	child_qr_b_0 = QueryResults(DataSet(["Child_0"],[["value_0"]]))
	child_qr_b_1 = QueryResults(DataSet(["Child_1"],[["value_1"]]))
	parent_qr_b.addNestedQueryResults("Child",[child_qr_b_1, child_qr_b_0])
	data["ParentB"] = parent_qr_b

Then examined the Preview pane:

<?xml version="1.0" ?>
<sample-data>
	<!--This is the raw data used to create the report preview.-->
	<ParentA>
		<row-0>
			<Row>0</Row>
			<Child>
				<row-0>
					<Child_1>value_1</Child_1>
				</row-0>
			</Child>
		</row-0>
		<row-1>
			<Row>1</Row>
			<Child>
				<row-0>
					<Child_0>value_0</Child_0>
				</row-0>
			</Child>
		</row-1>
	</ParentA>
	<ParentB>
		<row-0>
			<Row>0</Row>
			<Child>
				<row-0>
					<Child_1>value_1</Child_1>
				</row-0>
			</Child>
		</row-0>
		<row-1>
			<Row>1</Row>
			<Child>
				<row-0>
					<Child_0>value_0</Child_0>
				</row-0>
			</Child>
		</row-1>
	</ParentB>
	<Report>
		<Gateway>SGL-POTG1</Gateway>
		<Name>Report</Name>
		<Path>Report</Path>
		<Timestamp>2024-09-10 14:33:57.733</Timestamp>
	</Report>
</sample-data>
2

The data won't look any different. The parent is only used as a fallback if a query for rowIndex, columnName doesn't have anything on the core dataset:

    public Object lookup(int rowIndex, String keyName) {
        ColumnDispatcher column = getColumn(keyName);
        if (column.hasValue(rowIndex)) {
            return column.getValue(rowIndex);
        } else if (parent.isPresent()) {
            return parent.get().lookup(parentRow, keyName);
        } else {
            return null;
        }
    }
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