Show error when operations, but no stream selector (#47890)

public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.test.tsx

@@ -3,7 +3,7 @@ import { render, screen, getAllByRole, waitFor } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { LokiQueryBuilder } from './LokiQueryBuilder';
 import { LokiDatasource } from '../../datasource';
-import { LokiVisualQuery } from '../types';
+import { LokiOperationId, LokiVisualQuery } from '../types';
 import { PanelData } from '@grafana/data';
 
 const defaultQuery: LokiVisualQuery = {
@@ -17,10 +17,20 @@ describe('LokiQueryBuilder', () => {
     datasource.languageProvider.fetchSeriesLabels = jest.fn().mockReturnValue({ job: ['a'], instance: ['b'] });
     userEvent.click(screen.getByLabelText('Add'));
     const labels = screen.getByText(/Labels/);
-    const selects = getAllByRole(labels.parentElement!, 'combobox');
+    const selects = getAllByRole(labels.parentElement!.parentElement!.parentElement!, 'combobox');
     userEvent.click(selects[3]);
     await waitFor(() => expect(screen.getByText('job')).toBeInTheDocument());
   });
+
+  it('shows error for query with operations and no stream selector', async () => {
+    setup({ labels: [], operations: [{ id: LokiOperationId.Logfmt, params: [] }] });
+    expect(screen.getByText('You need to specify at least 1 label filter (stream selector)')).toBeInTheDocument();
+  });
+
+  it('shows no error for query with empty __line_contains operation and no stream selector', async () => {
+    setup({ labels: [], operations: [{ id: LokiOperationId.LineContains, params: [''] }] });
+    expect(screen.queryByText('You need to specify at least 1 label filter (stream selector)')).not.toBeInTheDocument();
+  });
 });
 
 function setup(query: LokiVisualQuery = defaultQuery, data?: PanelData) {

public/app/plugins/datasource/loki/querybuilder/components/LokiQueryBuilder.tsx

@@ -1,5 +1,5 @@
-import React from 'react';
+import React, { useMemo } from 'react';
-import { LokiVisualQuery } from '../types';
+import { LokiOperationId, LokiVisualQuery } from '../types';
 import { LokiDatasource } from '../../datasource';
 import { LabelFilters } from 'app/plugins/datasource/prometheus/querybuilder/shared/LabelFilters';
 import { OperationList } from 'app/plugins/datasource/prometheus/querybuilder/shared/OperationList';
@@ -57,6 +57,18 @@ export const LokiQueryBuilder = React.memo<Props>(({ datasource, query, nested,
     return result[forLabelInterpolated] ?? [];
   };
 
+  const labelFilterError: string | undefined = useMemo(() => {
+    const { labels, operations: op } = query;
+    if (!labels.length && op.length) {
+      // We don't want to show error for initial state with empty line contains operation
+      if (op.length === 1 && op[0].id === LokiOperationId.LineContains && op[0].params[0] === '') {
+        return undefined;
+      }
+      return 'You need to specify at least 1 label filter (stream selector)';
+    }
+    return undefined;
+  }, [query]);
+
   return (
     <>
       <EditorRow>
@@ -69,6 +81,7 @@ export const LokiQueryBuilder = React.memo<Props>(({ datasource, query, nested,
           }
           labelsFilters={query.labels}
           onChange={onChangeLabels}
+          error={labelFilterError}
         />
       </EditorRow>
       <OperationsEditorRow>

public/app/plugins/datasource/prometheus/querybuilder/shared/LabelFilters.tsx

@@ -1,5 +1,6 @@
 import { SelectableValue } from '@grafana/data';
-import { EditorField, EditorFieldGroup, EditorList } from '@grafana/experimental';
+import { EditorFieldGroup, EditorList } from '@grafana/experimental';
+import { Field } from '@grafana/ui';
 import { isEqual } from 'lodash';
 import React, { useEffect, useState } from 'react';
 import { QueryBuilderLabelFilter } from '../shared/types';
@@ -10,9 +11,10 @@ export interface Props {
   onChange: (labelFilters: QueryBuilderLabelFilter[]) => void;
   onGetLabelNames: (forLabel: Partial<QueryBuilderLabelFilter>) => Promise<SelectableValue[]>;
   onGetLabelValues: (forLabel: Partial<QueryBuilderLabelFilter>) => Promise<SelectableValue[]>;
+  error?: string;
 }
 
-export function LabelFilters({ labelsFilters, onChange, onGetLabelNames, onGetLabelValues }: Props) {
+export function LabelFilters({ labelsFilters, onChange, onGetLabelNames, onGetLabelValues, error }: Props) {
   const defaultOp = '=';
   const [items, setItems] = useState<Array<Partial<QueryBuilderLabelFilter>>>([{ op: defaultOp }]);
 
@@ -36,7 +38,7 @@ export function LabelFilters({ labelsFilters, onChange, onGetLabelNames, onGetLa
 
   return (
     <EditorFieldGroup>
-      <EditorField label="Labels">
+      <Field label="Labels" error={error} invalid={!!error}>
         <EditorList
           items={items}
           onChange={onLabelsChange}
@@ -51,7 +53,7 @@ export function LabelFilters({ labelsFilters, onChange, onGetLabelNames, onGetLa
             />
           )}
         />
-      </EditorField>
+      </Field>
     </EditorFieldGroup>
   );
 }

public/app/plugins/datasource/prometheus/querybuilder/testUtils.ts

@@ -2,7 +2,7 @@ import { screen, getAllByRole } from '@testing-library/react';
 
 export function getLabelSelects(index = 0) {
   const labels = screen.getByText(/Labels/);
-  const selects = getAllByRole(labels.parentElement!, 'combobox');
+  const selects = getAllByRole(labels.parentElement!.parentElement!.parentElement!, 'combobox');
   return {
     name: selects[3 * index],
     value: selects[3 * index + 2],