Expressions: More robust expression check (#65006)

More robust expression check

public/app/features/plugins/datasource_srv.ts

@@ -7,15 +7,15 @@ import {
   ScopedVars,
 } from '@grafana/data';
 import {
-  GetDataSourceListFilters,
   DataSourceSrv as DataSourceService,
-  getDataSourceSrv as getDataSourceService,
-  TemplateSrv,
-  getTemplateSrv,
-  getLegacyAngularInjector,
   getBackendSrv,
+  GetDataSourceListFilters,
+  getDataSourceSrv as getDataSourceService,
+  getLegacyAngularInjector,
+  getTemplateSrv,
+  TemplateSrv,
 } from '@grafana/runtime';
-import { ExpressionDatasourceRef } from '@grafana/runtime/src/utils/DataSourceWithBackend';
+import { ExpressionDatasourceRef, isExpressionReference } from '@grafana/runtime/src/utils/DataSourceWithBackend';
 import appEvents from 'app/core/app_events';
 import config from 'app/core/config';
 import {
@@ -80,6 +80,13 @@ export class DatasourceSrv implements DataSourceService {
       return this.settingsMapByUid[this.defaultName] ?? this.settingsMapByName[this.defaultName];
     }
 
+    // Expressions has a new UID as __expr__ See: https://github.com/grafana/grafana/pull/62510/
+    // But we still have dashboards/panels with old expression UID (-100)
+    // To support both UIDs until we migrate them all to new one, this check is necessary
+    if (isExpressionReference(nameOrUid)) {
+      return expressionDatasource.instanceSettings;
+    }
+
     // Complex logic to support template variable data source names
     // For this we just pick the current or first data source in the variable
     if (nameOrUid[0] === '$') {

public/app/features/plugins/tests/datasource_srv.test.ts

@@ -5,6 +5,7 @@ import {
   DataSourcePluginMeta,
   ScopedVar,
 } from '@grafana/data';
+import { ExpressionDatasourceRef } from '@grafana/runtime/src/utils/DataSourceWithBackend';
 import { DatasourceSrv } from 'app/features/plugins/datasource_srv';
 
 // Datasource variable $datasource with current value 'BBB'
@@ -199,6 +200,25 @@ describe('datasource_srv', () => {
           }
         `);
       });
+
+      it('should return expression settings with either expression UIDs', () => {
+        const exprWithOldUID = dataSourceSrv.getInstanceSettings('-100');
+        expect(exprWithOldUID?.name).toBe('Expression');
+        expect(exprWithOldUID?.uid).toBe(ExpressionDatasourceRef.uid);
+        expect(exprWithOldUID?.type).toBe(ExpressionDatasourceRef.type);
+
+        const exprWithNewUID = dataSourceSrv.getInstanceSettings('__expr__');
+        expect(exprWithNewUID?.name).toBe('Expression');
+        expect(exprWithNewUID?.uid).toBe(ExpressionDatasourceRef.uid);
+        expect(exprWithNewUID?.type).toBe(ExpressionDatasourceRef.type);
+      });
+
+      it('should return expression settings with expression name', () => {
+        const exprWithName = dataSourceSrv.getInstanceSettings('Expression');
+        expect(exprWithName?.name).toBe(ExpressionDatasourceRef.name);
+        expect(exprWithName?.uid).toBe(ExpressionDatasourceRef.uid);
+        expect(exprWithName?.type).toBe(ExpressionDatasourceRef.type);
+      });
     });
 
     describe('when getting external metric sources', () => {