Datasources: Add support for getDetDefaultQuery in variable editor (#62026)

+Cloudwatch implementation

packages/grafana-data/src/types/variables.ts

@@ -35,6 +35,11 @@ export abstract class VariableSupportBase<
   TOptions extends DataSourceJsonData = DataSourceOptionsType<DSType>
 > {
   abstract getType(): VariableSupportType;
+
+  /**
+   * Define this method in the config if you want to pre-populate the editor with a default query.
+   */
+  getDefaultQuery?(): Partial<TQuery>;
 }
 
 /**

public/app/features/variables/query/QueryVariableEditor.test.tsx

@@ -2,7 +2,7 @@ import { render, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import React from 'react';
 
-import { DataSourceApi } from '@grafana/data';
+import { DataSourceApi, VariableSupportType } from '@grafana/data';
 import { mockDataSource } from 'app/features/alerting/unified/mocks';
 import { DataSourceType } from 'app/features/alerting/unified/utils/datasource';
 
@@ -64,6 +64,42 @@ describe('QueryVariableEditor', () => {
     });
   });
 
+  describe('when the editor is rendered', () => {
+    const extendedCustom = {
+      extended: {
+        VariableQueryEditor: jest.fn().mockImplementation(LegacyVariableQueryEditor),
+        dataSource: {
+          variables: {
+            getType: () => VariableSupportType.Custom,
+            query: jest.fn(),
+            editor: jest.fn(),
+          },
+        } as unknown as DataSourceApi,
+      },
+    };
+    it('should pass down the query with default values if the datasource config defines it', () => {
+      const extended = { ...extendedCustom };
+      extended.extended.dataSource.variables!.getDefaultQuery = jest
+        .fn()
+        .mockImplementation(() => 'some default query');
+      const { props } = setupTestContext(extended);
+      expect(props.extended?.dataSource?.variables?.getDefaultQuery).toBeDefined();
+      expect(props.extended?.dataSource?.variables?.getDefaultQuery).toHaveBeenCalledTimes(1);
+      expect(props.extended?.VariableQueryEditor).toHaveBeenCalledWith(
+        expect.objectContaining({ query: 'some default query' }),
+        expect.anything()
+      );
+    });
+    it('should not pass down a default query if the datasource config doesnt define it', () => {
+      extendedCustom.extended.dataSource.variables!.getDefaultQuery = undefined;
+      const { props } = setupTestContext(extendedCustom);
+      expect(props.extended?.dataSource?.variables?.getDefaultQuery).not.toBeDefined();
+      expect(props.extended?.VariableQueryEditor).toHaveBeenCalledWith(
+        expect.objectContaining({ query: '' }),
+        expect.anything()
+      );
+    });
+  });
   describe('when the user changes', () => {
     it.each`
       fieldName  | propName                      | expectedArgs

public/app/features/variables/query/QueryVariableEditor.tsx

@@ -134,10 +134,20 @@ export class QueryVariableEditorUnConnected extends PureComponent<Props, State>
       return null;
     }
 
-    const query = variable.query;
     const datasource = extended.dataSource;
     const VariableQueryEditor = extended.VariableQueryEditor;
 
+    let query = variable.query;
+
+    if (typeof query === 'string') {
+      query = query || (datasource.variables?.getDefaultQuery?.() ?? '');
+    } else {
+      query = {
+        ...datasource.variables?.getDefaultQuery?.(),
+        ...variable.query,
+      };
+    }
+
     if (isLegacyQueryEditor(VariableQueryEditor, datasource)) {
       return (
         <Field label="Query">

public/app/plugins/datasource/cloudwatch/defaultQueries.ts

@@ -1,4 +1,12 @@
-import { CloudWatchLogsQuery, CloudWatchMetricsQuery, LogGroup, MetricEditorMode, MetricQueryType } from './types';
+import {
+  CloudWatchLogsQuery,
+  CloudWatchMetricsQuery,
+  LogGroup,
+  MetricEditorMode,
+  MetricQueryType,
+  VariableQuery,
+  VariableQueryType,
+} from './types';
 
 export const DEFAULT_METRICS_QUERY: Omit<CloudWatchMetricsQuery, 'refId'> = {
   queryMode: 'Metrics',
@@ -29,3 +37,8 @@ export const getDefaultLogsQuery = (
   logGroupNames: legacyDefaultLogGroups,
   logGroups: defaultLogGroups ?? [],
 });
+
+export const DEFAULT_VARIABLE_QUERY: Partial<VariableQuery> = {
+  queryType: VariableQueryType.Regions,
+  region: 'default',
+};

public/app/plugins/datasource/cloudwatch/variables.ts

@@ -12,6 +12,7 @@ import {
 import { ALL_ACCOUNTS_OPTION } from './components/Account';
 import { VariableQueryEditor } from './components/VariableQueryEditor/VariableQueryEditor';
 import { CloudWatchDatasource } from './datasource';
+import { DEFAULT_VARIABLE_QUERY } from './defaultQueries';
 import { migrateVariableQuery } from './migrations/variableQueryMigrations';
 import { ResourcesAPI } from './resources/ResourcesAPI';
 import { standardStatistics } from './standardStatistics';
@@ -158,6 +159,10 @@ export class CloudWatchVariableSupport extends CustomVariableSupport<CloudWatchD
       return metricFindOptions.length ? [this.allMetricFindValue, ...metricFindOptions] : [];
     });
   }
+
+  getDefaultQuery(): Partial<VariableQuery> {
+    return DEFAULT_VARIABLE_QUERY;
+  }
 }
 
 function selectableValueToMetricFindOption({ label, value }: SelectableValue<string>): MetricFindValue {