From da03175d0b8a8aa41c5f2e397a754a8d04d29344 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotr=20Jamr=C3=B3z?= <pm.jamroz@gmail.com>
Date: Fri, 16 Apr 2021 08:32:33 +0200
Subject: [PATCH] Explore: Load default data source in Explore when the
 provided source does not exist (#32992)

* Fallback to default data source in Explore and use uid for history

uid is used to allow changing the name of the datasource and preserve history

* Remove redundant console logs
---
 .../app/features/explore/state/explorePane.ts |  4 +-
 .../app/features/explore/state/utils.test.ts  | 49 +++++++++++++++++++
 public/app/features/explore/state/utils.ts    | 12 ++++-
 3 files changed, 61 insertions(+), 4 deletions(-)
 create mode 100644 public/app/features/explore/state/utils.test.ts

diff --git a/public/app/features/explore/state/explorePane.ts b/public/app/features/explore/state/explorePane.ts
index b82abd4b8df..0db25a83fd2 100644
--- a/public/app/features/explore/state/explorePane.ts
+++ b/public/app/features/explore/state/explorePane.ts
@@ -127,7 +127,7 @@ export const changeDedupStrategy = (
  */
 export function initializeExplore(
   exploreId: ExploreId,
-  datasourceName: string,
+  datasourceNameOrUid: string,
   queries: DataQuery[],
   range: TimeRange,
   containerWidth: number,
@@ -141,7 +141,7 @@ export function initializeExplore(
 
     if (exploreDatasources.length >= 1) {
       const orgId = getState().user.orgId;
-      const loadResult = await loadAndInitDatasource(orgId, datasourceName);
+      const loadResult = await loadAndInitDatasource(orgId, datasourceNameOrUid);
       instance = loadResult.instance;
       history = loadResult.history;
     }
diff --git a/public/app/features/explore/state/utils.test.ts b/public/app/features/explore/state/utils.test.ts
new file mode 100644
index 00000000000..401ec79924d
--- /dev/null
+++ b/public/app/features/explore/state/utils.test.ts
@@ -0,0 +1,49 @@
+import { lastUsedDatasourceKeyForOrgId } from '../../../core/utils/explore';
+
+const dataSourceMock = {
+  get: jest.fn(),
+};
+jest.mock('app/features/plugins/datasource_srv', () => ({
+  getDatasourceSrv: jest.fn(() => dataSourceMock),
+}));
+
+const storeMock = {
+  getObject: jest.fn().mockReturnValue([]),
+  set: jest.fn(),
+};
+jest.mock('app/core/store', () => storeMock);
+
+import { loadAndInitDatasource } from './utils';
+
+const DEFAULT_DATASOURCE = { uid: 'abc123', name: 'Default' };
+const TEST_DATASOURCE = { uid: 'def789', name: 'Test' };
+
+describe('loadAndInitDatasource', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('falls back to default datasource if the provided one was not found', async () => {
+    dataSourceMock.get.mockRejectedValueOnce(new Error('Datasource not found'));
+    dataSourceMock.get.mockResolvedValue(DEFAULT_DATASOURCE);
+
+    const { instance } = await loadAndInitDatasource(1, 'Unknown');
+
+    expect(dataSourceMock.get).toBeCalledTimes(2);
+    expect(dataSourceMock.get).toBeCalledWith('Unknown');
+    expect(dataSourceMock.get).toBeCalledWith();
+    expect(instance).toMatchObject(DEFAULT_DATASOURCE);
+    expect(storeMock.set).toBeCalledWith(lastUsedDatasourceKeyForOrgId(1), DEFAULT_DATASOURCE.uid);
+  });
+
+  it('saves last loaded data source uid', async () => {
+    dataSourceMock.get.mockResolvedValue(TEST_DATASOURCE);
+
+    const { instance } = await loadAndInitDatasource(1, 'Test');
+
+    expect(dataSourceMock.get).toBeCalledTimes(1);
+    expect(dataSourceMock.get).toBeCalledWith('Test');
+    expect(instance).toMatchObject(TEST_DATASOURCE);
+    expect(storeMock.set).toBeCalledWith(lastUsedDatasourceKeyForOrgId(1), TEST_DATASOURCE.uid);
+  });
+});
diff --git a/public/app/features/explore/state/utils.ts b/public/app/features/explore/state/utils.ts
index c25d49199a3..c7373f63b19 100644
--- a/public/app/features/explore/state/utils.ts
+++ b/public/app/features/explore/state/utils.ts
@@ -63,7 +63,15 @@ export async function loadAndInitDatasource(
   orgId: number,
   datasourceName?: string
 ): Promise<{ history: HistoryItem[]; instance: DataSourceApi }> {
-  const instance = await getDatasourceSrv().get(datasourceName);
+  let instance;
+  try {
+    instance = await getDatasourceSrv().get(datasourceName);
+  } catch (error) {
+    // Falling back to the default data source in case the provided data source was not found.
+    // It may happen if last used data source or the data source provided in the URL has been
+    // removed or it is not provisioned anymore.
+    instance = await getDatasourceSrv().get();
+  }
   if (instance.init) {
     try {
       instance.init();
@@ -77,7 +85,7 @@ export async function loadAndInitDatasource(
   const history = store.getObject(historyKey, []);
   // Save last-used datasource
 
-  store.set(lastUsedDatasourceKeyForOrgId(orgId), instance.name);
+  store.set(lastUsedDatasourceKeyForOrgId(orgId), instance.uid);
   return { history, instance };
 }