Fix: Parse exemplars before parsing heatmap data (#47463) (#47469)

* parse exemplars before parsing the heatmap. Exemplars are overlayed. Not part of the main heatmap

* added tests

(cherry picked from commit 222325c7f1)

Co-authored-by: Stephanie Closson <srclosson@gmail.com>

public/app/plugins/datasource/prometheus/result_transformer.test.ts

@@ -251,6 +251,71 @@ describe('Prometheus Result Transformer', () => {
       expect(series.data[0].fields[2].values.toArray()).toEqual([10, 0, 30]);
       expect(series.data[0].fields[3].values.toArray()).toEqual([10, 0, 10]);
     });
+
+    it('Retains exemplar frames when data returned is a heatmap', () => {
+      const options = {
+        targets: [
+          {
+            format: 'heatmap',
+            refId: 'A',
+          },
+        ],
+      } as unknown as DataQueryRequest<PromQuery>;
+      const response = {
+        state: 'Done',
+        data: [
+          new MutableDataFrame({
+            refId: 'A',
+            fields: [
+              { name: 'Time', type: FieldType.time, values: [6, 5, 4] },
+              {
+                name: 'Value',
+                type: FieldType.number,
+                values: [10, 10, 0],
+                labels: { le: '1' },
+              },
+            ],
+          }),
+          new MutableDataFrame({
+            refId: 'A',
+            name: 'exemplar',
+            meta: {
+              custom: {
+                resultType: 'exemplar',
+              },
+            },
+            fields: [
+              { name: 'Time', type: FieldType.time, values: [6, 5, 4, 3, 2, 1] },
+              {
+                name: 'Value',
+                type: FieldType.number,
+                values: [30, 10, 40, 90, 14, 21],
+                labels: { le: '6' },
+              },
+              {
+                name: 'Test',
+                type: FieldType.string,
+                values: ['hello', 'doctor', 'name', 'continue', 'yesterday', 'tomorrow'],
+                labels: { le: '6' },
+              },
+            ],
+          }),
+        ],
+      } as unknown as DataQueryResponse;
+
+      const series = transformV2(response, options, {});
+      expect(series.data[0].fields.length).toEqual(2);
+      expect(series.data.length).toEqual(2);
+      expect(series.data[1].fields[2].values.toArray()).toEqual([
+        'hello',
+        'doctor',
+        'name',
+        'continue',
+        'yesterday',
+        'tomorrow',
+      ]);
+      expect(series.data[1].fields.length).toEqual(3);
+    });
   });
   describe('transformDFToTable', () => {
     it('transforms dataFrame with response length 1 to table dataFrame', () => {

public/app/plugins/datasource/prometheus/result_transformer.ts

@@ -72,16 +72,8 @@ export function transformV2(
   const [tableFrames, framesWithoutTable] = partition<DataFrame>(response.data, (df) => isTableResult(df, request));
   const processedTableFrames = transformDFToTable(tableFrames);
 
-  const [heatmapResults, framesWithoutTableAndHeatmaps] = partition<DataFrame>(framesWithoutTable, (df) =>
+  const [exemplarFrames, framesWithoutTableAndExemplars] = partition<DataFrame>(
-    isHeatmapResult(df, request)
+    framesWithoutTable,
-  );
-
-  const processedHeatmapFrames = mergeHeatmapFrames(
-    transformToHistogramOverTime(heatmapResults.sort(sortSeriesByLabel))
-  );
-
-  const [exemplarFrames, framesWithoutTableHeatmapsAndExemplars] = partition<DataFrame>(
-    framesWithoutTableAndHeatmaps,
     (df) => df.meta?.custom?.resultType === 'exemplar'
   );
 
@@ -103,6 +95,15 @@ export function transformV2(
     return { ...dataFrame, meta: { ...dataFrame.meta, dataTopic: DataTopic.Annotations } };
   });
 
+  const [heatmapResults, framesWithoutTableHeatmapsAndExemplars] = partition<DataFrame>(
+    framesWithoutTableAndExemplars,
+    (df) => isHeatmapResult(df, request)
+  );
+
+  const processedHeatmapFrames = mergeHeatmapFrames(
+    transformToHistogramOverTime(heatmapResults.sort(sortSeriesByLabel))
+  );
+
   // Everything else is processed as time_series result and graph preferredVisualisationType
   const otherFrames = framesWithoutTableHeatmapsAndExemplars.map((dataFrame) => {
     const df = {