Logs: Always keep displayed fields with changed queries (#102493)

* Logs: Always keep displayed fields with changed queries

* Remove unused var

public/app/features/explore/Logs/Logs.tsx

@@ -82,7 +82,7 @@ import { LogsMetaRow } from './LogsMetaRow';
 import LogsNavigation from './LogsNavigation';
 import { LogsTableWrap, getLogsTableHeight } from './LogsTableWrap';
 import { LogsVolumePanelList } from './LogsVolumePanelList';
-import { canKeepDisplayedFields, SETTINGS_KEYS, visualisationTypeKey } from './utils/logs';
+import { SETTINGS_KEYS, visualisationTypeKey } from './utils/logs';
 
 interface Props extends Themeable2 {
   width: number;
@@ -225,7 +225,6 @@ const UnthemedLogs: React.FunctionComponent<Props> = (props: Props) => {
   const cancelFlippingTimer = useRef<number | undefined>(undefined);
   const toggleLegendRef = useRef<(name: string, mode: SeriesVisibilityChangeMode) => void>(() => {});
   const topLogsRef = useRef<HTMLDivElement>(null);
-  const prevLogsQueries = usePrevious(logsQueries);
 
   const tableHeight = getLogsTableHeight();
   const styles = getStyles(theme, wrapLogMessage, tableHeight);
@@ -409,20 +408,6 @@ const UnthemedLogs: React.FunctionComponent<Props> = (props: Props) => {
     ]
   );
 
-  useEffect(() => {
-    if (!prevLogsQueries) {
-      // Initial load, ignore
-      return;
-    }
-    if (!canKeepDisplayedFields(logsQueries, prevLogsQueries)) {
-      setDisplayedFields([]);
-      updatePanelState({
-        ...panelState?.logs,
-        displayedFields: [],
-      });
-    }
-  }, [logsQueries, panelState?.logs, prevLogsQueries, updatePanelState]);
-
   // actions
   const onLogRowHover = useCallback(
     (row?: LogRowModel) => {

public/app/features/explore/Logs/utils/logs.test.ts

@@ -1,27 +0,0 @@
-import { DataQuery } from '@grafana/data';
-
-import { canKeepDisplayedFields } from './logs';
-
-describe('canKeepDisplayedFields', () => {
-  test('Returns false when passing no queries', () => {
-    expect(canKeepDisplayedFields(undefined, [])).toBe(false);
-  });
-
-  test('Returns false when some prev queries are undefined', () => {
-    const logQueries: DataQuery[] = [{ refId: 'A' }, { refId: 'B' }];
-    const prevLogQueries = [{ refId: 'C' }];
-    expect(canKeepDisplayedFields(logQueries, prevLogQueries)).toBe(false);
-  });
-
-  test('Returns false when some new queries are undefined', () => {
-    const logQueries: DataQuery[] = [{ refId: 'A' }];
-    const prevLogQueries = [{ refId: 'C' }, { refId: 'B' }];
-    expect(canKeepDisplayedFields(logQueries, prevLogQueries)).toBe(false);
-  });
-
-  test('Returns true when the queries exactly match', () => {
-    const logQueries: DataQuery[] = [{ refId: 'C' }, { refId: 'B' }];
-    const prevLogQueries = [{ refId: 'C' }, { refId: 'B' }];
-    expect(canKeepDisplayedFields(logQueries, prevLogQueries)).toBe(true);
-  });
-});

public/app/features/explore/Logs/utils/logs.ts

@@ -1,6 +1,3 @@
-import { shallowCompare } from '@grafana/data';
-import { DataQuery } from '@grafana/schema';
-
 export const SETTINGS_KEYS = {
   showLabels: 'grafana.explore.logs.showLabels',
   showTime: 'grafana.explore.logs.showTime',
@@ -11,15 +8,3 @@ export const SETTINGS_KEYS = {
 };
 
 export const visualisationTypeKey = 'grafana.explore.logs.visualisationType';
-
-export const canKeepDisplayedFields = (logsQueries: DataQuery[] | undefined, prevLogsQueries: DataQuery[]): boolean => {
-  if (!logsQueries) {
-    return false;
-  }
-  for (let i = 0; i < logsQueries.length; i++) {
-    if (!logsQueries[i] || !prevLogsQueries[i] || !shallowCompare(logsQueries[i], prevLogsQueries[i])) {
-      return false;
-    }
-  }
-  return true;
-};