PanelEdit: Fixed re-using query result after leaving panel edit (#24340)

public/app/features/dashboard/components/PanelEditor/state/actions.ts

@@ -58,10 +58,7 @@ export function panelEditorCleanUp(): ThunkResult<void> {
       // Resend last query result on source panel query runner
       // But do this after the panel edit editor exit process has completed
       setTimeout(() => {
-        const lastResult = panel.getQueryRunner().getLastResult();
-        if (lastResult) {
-          sourcePanel.getQueryRunner().pipeDataToSubject(lastResult);
-        }
+        sourcePanel.getQueryRunner().useLastResultFrom(panel.getQueryRunner());
       }, 20);
     }
 

public/app/features/dashboard/dashgrid/PanelChrome.tsx

@@ -235,10 +235,6 @@ export class PanelChrome extends PureComponent<Props, State> {
     return panel.snapshotData && panel.snapshotData.length;
   }
 
-  panelHasLastResult = () => {
-    return !!this.props.panel.getQueryRunner().getLastResult();
-  };
-
   get wantsQueryExecution() {
     return !(this.props.plugin.meta.skipDataQuery || this.hasPanelSnapshot);
   }

public/app/features/dashboard/state/PanelModel.test.ts

@@ -6,8 +6,10 @@ import {
   PanelProps,
   standardEditorsRegistry,
   standardFieldConfigEditorRegistry,
+  PanelData,
 } from '@grafana/data';
 import { ComponentClass } from 'react';
+import { PanelQueryRunner } from './PanelQueryRunner';
 
 class TablePanelCtrl {}
 
@@ -336,5 +338,16 @@ describe('PanelModel', () => {
         expect(model.thresholds).toBeUndefined();
       });
     });
+
+    describe('destroy', () => {
+      it('Should still preserve last query result', () => {
+        model.getQueryRunner().useLastResultFrom({
+          getLastResult: () => ({} as PanelData),
+        } as PanelQueryRunner);
+
+        model.destroy();
+        expect(model.getQueryRunner().getLastResult()).toBeDefined();
+      });
+    });
   });
 });

public/app/features/dashboard/state/PanelModel.ts

@@ -422,11 +422,8 @@ export class PanelModel implements DataConfigSource {
     clone.isEditing = true;
     const sourceQueryRunner = this.getQueryRunner();
 
-    // pipe last result to new clone query runner
-    const lastResult = sourceQueryRunner.getLastResult();
-    if (lastResult) {
-      clone.getQueryRunner().pipeDataToSubject(lastResult);
-    }
+    // Copy last query result
+    clone.getQueryRunner().useLastResultFrom(sourceQueryRunner);
 
     return clone;
   }
@@ -469,7 +466,6 @@ export class PanelModel implements DataConfigSource {
 
     if (this.queryRunner) {
       this.queryRunner.destroy();
-      this.queryRunner = null;
     }
   }
 

public/app/features/dashboard/state/PanelQueryRunner.ts

@@ -190,11 +190,6 @@ export class PanelQueryRunner {
     });
   }
 
-  pipeDataToSubject = (data: PanelData) => {
-    this.subject.next(data);
-    this.lastResult = data;
-  };
-
   resendLastResult = () => {
     if (this.lastResult) {
       this.subject.next(this.lastResult);
@@ -215,6 +210,15 @@ export class PanelQueryRunner {
     }
   }
 
+  useLastResultFrom(runner: PanelQueryRunner) {
+    this.lastResult = runner.getLastResult();
+
+    if (this.lastResult) {
+      // The subject is a replay subject so anyone subscribing will get this last result
+      this.subject.next(this.lastResult);
+    }
+  }
+
   getLastResult(): PanelData {
     return this.lastResult;
   }