fix(Summarize Node): Return null instead of NaN for an average with no numeric values (#41430)

packages/nodes-base/nodes/Transform/Summarize/test/unitTests/splitData.test.ts

@@ -311,4 +311,32 @@ describe('Test Summarize Node, aggregateAndSplitData', () => {
 			expect(flattenAggregationResultToArray(result)).toMatchSnapshot('array');
 		});
 	});
+
+	test('should return null, not NaN, for the average of a group with no numeric values', () => {
+		const data = [
+			{ Sku: 'A', Qty: 2, _itemIndex: 0 },
+			{ Sku: 'A', Qty: 4, _itemIndex: 1 },
+			{ Sku: 'B', Qty: 'n/a', _itemIndex: 2 },
+			{ Sku: 'B', Qty: '', _itemIndex: 3 },
+		];
+
+		const aggregations: Aggregations = [
+			{ aggregation: 'average', field: 'Qty' },
+			{ aggregation: 'sum', field: 'Qty' },
+		];
+
+		const result = aggregateAndSplitData({
+			splitKeys: ['Sku'],
+			inputItems: data,
+			fieldsToSummarize: aggregations,
+			options: { continueIfFieldNotFound: true },
+			getValue: fieldValueGetter(),
+		});
+
+		// Sum keeps returning 0, the identity for a sum, for a group with no numeric values.
+		expect(flattenAggregationResultToArray(result)).toEqual([
+			{ returnData: { Sku: 'A', average_Qty: 3, sum_Qty: 6 }, pairedItems: [0, 1] },
+			{ returnData: { Sku: 'B', average_Qty: null, sum_Qty: 0 }, pairedItems: [2, 3] },
+		]);
+	});
 });

packages/nodes-base/nodes/Transform/Summarize/utils.ts

@@ -122,6 +122,11 @@ function aggregate(items: IDataObject[], entry: Aggregation, getValue: ValueGett
 
 		//numerical operations
 		case 'average':
+			// No numeric values to average: report null like min and max do,
+			// instead of the NaN that 0 / 0 would give.
+			if (data.length === 0) {
+				return null;
+			}
 			return (
 				data.reduce((acc, item) => {
 					return acc + (getValue(item, field) as number);