api/ds/query: simplify data sources lookup for queries and expressions (#41172)

packages/grafana-runtime/src/utils/DataSourceWithBackend.ts

@@ -11,13 +11,32 @@ import {
   parseLiveChannelAddress,
   StreamingFrameOptions,
   StreamingFrameAction,
+  getDataSourceRef,
+  DataSourceRef,
 } from '@grafana/data';
 import { merge, Observable, of } from 'rxjs';
 import { catchError, switchMap } from 'rxjs/operators';
 import { getBackendSrv, getDataSourceSrv, getGrafanaLiveSrv } from '../services';
 import { BackendDataSourceResponse, toDataQueryResponse } from './queryResponse';
 
-const ExpressionDatasourceID = '__expr__';
+/**
+ * @internal
+ */
+export const ExpressionDatasourceRef = Object.freeze({
+  type: '__expr__',
+  uid: '__expr__',
+});
+
+/**
+ * @internal
+ */
+export function isExpressionReference(ref?: DataSourceRef | string | null): boolean {
+  if (!ref) {
+    return false;
+  }
+  const v = (ref as any).type ?? ref;
+  return v === ExpressionDatasourceRef.type || v === '-100'; // -100 was a legacy accident that should be removed
+}
 
 class HealthCheckError extends Error {
   details: HealthCheckResultDetails;
@@ -89,12 +108,12 @@ class DataSourceWithBackend<
     }
 
     const queries = targets.map((q) => {
-      let datasourceId = this.id;
+      let datasource = this.getRef();
 
-      if (q.datasource === ExpressionDatasourceID) {
+      if (isExpressionReference(q.datasource)) {
         return {
           ...q,
-          datasourceId,
+          datasource: ExpressionDatasourceRef,
         };
       }
 
@@ -105,12 +124,12 @@ class DataSourceWithBackend<
           throw new Error(`Unknown Datasource: ${JSON.stringify(q.datasource)}`);
         }
 
-        datasourceId = ds.id;
+        datasource = getDataSourceRef(ds);
       }
 
       return {
         ...this.applyTemplateVariables(q, request.scopedVars),
-        datasourceId,
+        datasource,
         intervalMs,
         maxDataPoints,
       };