From 07e403d8ee110fafb8aab586537e53dfbb91bffe Mon Sep 17 00:00:00 2001
From: GagandeepSingh20 <gchoudhary16555@gmail.com>
Date: Mon, 22 Jun 2026 14:08:57 +0530
Subject: [PATCH] fix(sqllab): preserve database state on SET_DATABASES

---
 .../src/SqlLab/reducers/sqlLab.test.ts        | 42 ++++++++++++++++++-
 .../src/SqlLab/reducers/sqlLab.ts             |  8 +++-
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/superset-frontend/src/SqlLab/reducers/sqlLab.test.ts b/superset-frontend/src/SqlLab/reducers/sqlLab.test.ts
index eacbe65ea83e..742f10da0e48 100644
--- a/superset-frontend/src/SqlLab/reducers/sqlLab.test.ts
+++ b/superset-frontend/src/SqlLab/reducers/sqlLab.test.ts
@@ -21,13 +21,53 @@ import sqlLabReducer from 'src/SqlLab/reducers/sqlLab';
 import * as actions from 'src/SqlLab/actions/sqlLab';
 import type { SqlLabAction } from 'src/SqlLab/actions/sqlLab';
 import type { SqlLabRootState } from 'src/SqlLab/types';
-import { table, initialState as mockState } from '../fixtures';
+import {
+  table,
+  databases,
+  initialState as mockState,
+} from '../fixtures';
 
 type SqlLabState = SqlLabRootState['sqlLab'];
 const initialState = mockState.sqlLab as unknown as SqlLabState;
 
 // eslint-disable-next-line no-restricted-globals -- TODO: Migrate from describe blocks
 describe('sqlLabReducer', () => {
+  describe('Database actions', () => {
+    test('should merge databases instead of replacing existing database state', () => {
+      const existingDb = databases.result[0];
+      const incomingDb = databases.result[1];
+  
+      const state = {
+        ...initialState,
+        databases: {
+          [existingDb.id]: {
+            ...existingDb,
+            extra_json: {},
+          },
+        },
+      };
+  
+      const action = actions.setDatabases([
+        {
+          ...incomingDb,
+          extra: '{}',
+        },
+      ] as any);
+  
+      const newState = sqlLabReducer(state as any, action);
+  
+      expect(newState.databases[existingDb.id]).toBeDefined();
+      expect(newState.databases[incomingDb.id]).toBeDefined();
+  
+      expect(
+        newState.databases[existingDb.id].database_name,
+      ).toBe(existingDb.database_name);
+  
+      expect(
+        newState.databases[incomingDb.id].database_name,
+      ).toBe(incomingDb.database_name);
+    });
+  });
   // eslint-disable-next-line no-restricted-globals -- TODO: Migrate from describe blocks
   describe('Query editors actions', () => {
     let newState: SqlLabState;
diff --git a/superset-frontend/src/SqlLab/reducers/sqlLab.ts b/superset-frontend/src/SqlLab/reducers/sqlLab.ts
index 34e3af847ccf..577406c99dbd 100644
--- a/superset-frontend/src/SqlLab/reducers/sqlLab.ts
+++ b/superset-frontend/src/SqlLab/reducers/sqlLab.ts
@@ -718,7 +718,13 @@ export default function sqlLabReducer(
           extra_json: JSON.parse(db.extra || ''),
         };
       });
-      return { ...state, databases };
+      return {
+        ...state,
+        databases: {
+          ...state.databases,
+          ...databases,
+        },
+      };
     },
     [actions.REFRESH_QUERIES]() {
       let newQueries = { ...state.queries };