From a01b4c31a1fe358420095e0278b10437e8425e8a Mon Sep 17 00:00:00 2001
From: Kristina <kristina.durivage@grafana.com>
Date: Thu, 10 Jul 2025 18:47:18 -0500
Subject: [PATCH] Transformations: Allow queries without dataframe results to
 be selectable as filters (#107152)
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* Add mention of external type to correlations docs

* 🆗

* Merge request targets in with results

* Ensure we do not mutate result set
---
 .../TransformationOperationRow.tsx                   | 12 +++++++++++-
 .../TransformationsEditor/TransformationsEditor.tsx  |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/public/app/features/dashboard/components/TransformationsEditor/TransformationOperationRow.tsx b/public/app/features/dashboard/components/TransformationsEditor/TransformationOperationRow.tsx
index b77e0f41620..bebae5de3e2 100644
--- a/public/app/features/dashboard/components/TransformationsEditor/TransformationOperationRow.tsx
+++ b/public/app/features/dashboard/components/TransformationsEditor/TransformationOperationRow.tsx
@@ -138,7 +138,17 @@ export const TransformationOperationRow = ({
       .subscribe(setOutput);
     const prevOutputSubscription = transformDataFrame(prevInputTransforms, data.series, ctx)
       .pipe(mergeMap((before) => transformDataFrame(prevOutputTransforms, before, ctx)))
-      .subscribe(setPrevOutput);
+      .subscribe((result) => {
+        let mergedResult = [...result];
+        // add refIds that were requested even if they did not return a result
+        data.request?.targets.forEach((series) => {
+          const refIdInResult = mergedResult.some((frame) => frame.refId === series.refId);
+          if (!refIdInResult) {
+            mergedResult.push({ refId: series.refId, fields: [], length: 0 });
+          }
+        });
+        setPrevOutput(mergedResult);
+      });
 
     return function unsubscribe() {
       inputSubscription.unsubscribe();
diff --git a/public/app/features/dashboard/components/TransformationsEditor/TransformationsEditor.tsx b/public/app/features/dashboard/components/TransformationsEditor/TransformationsEditor.tsx
index 17d18efba74..afdf6b782ea 100644
--- a/public/app/features/dashboard/components/TransformationsEditor/TransformationsEditor.tsx
+++ b/public/app/features/dashboard/components/TransformationsEditor/TransformationsEditor.tsx
@@ -5,6 +5,7 @@ import { Unsubscribable } from 'rxjs';
 
 import {
   DataFrame,
+  DataQueryRequest,
   DataTransformerConfig,
   PanelData,
   SelectableValue,
@@ -44,6 +45,7 @@ export type viewAllType = 'viewAll';
 export type FilterCategory = TransformerCategory | viewAllType;
 
 export interface TransformationData {
+  request?: DataQueryRequest;
   series: DataFrame[];
   annotations?: DataFrame[];
 }