feat(realtime): Implement real-time updates for shopping list

Introduces WebSocket-based real-time updates for the shopping list.
Changes to items (add, mark, delete) are now instantly reflected
across all connected user sessions without requiring a page refresh.

This commit:
- Extends the WebSocket ConnectionManager to broadcast item updates.
- Modifies item manipulation endpoints (add, mark, delete) to trigger broadcasts.
- Updates the frontend to listen for update broadcasts and refresh the list.
- Updates README.md to reflect the new real-time update feature.

README.md

@@ -11,7 +11,7 @@ This web service is the final development step for the accompanying **Android ap
 ## Features
 
 *   **Multi-user access:** Log in to manage the list. Includes an admin panel for user management.
-*   **Real-time updates:** The list updates in real-time for all connected users.
+*   **Real-time updates:** Changes to the shopping list (add, mark, delete) are instantly reflected across all connected user sessions.
 *   **Automatic Language Detection:** The user interface automatically adapts to your browser's language. Currently, English and German are supported. Simply refresh the page after changing your browser or OS language settings.
 *   **Gotify Notifications:** Trigger notifications to your Gotify server.
 *   **Suggestion Box:** Get suggestions for items as you type.

main.py

@@ -89,6 +89,10 @@ class ConnectionManager:
         for connection in self.active_connections:
             await connection.send_json({"type": "user_list", "users": user_list})
 
+    async def broadcast_update(self):
+        for connection in self.active_connections:
+            await connection.send_json({"type": "update"})
+
 
 manager = ConnectionManager()
 
@@ -501,8 +505,11 @@ async def add_item(item: Item, current_user: UserInDB = Depends(get_current_acti
     conn.close()
 
     if added_count > 0:
+        await manager.broadcast_update()
+        conn.close()
         return {"status": "ok", "added": added_count}
     else:
+        conn.close()
         return {"status": "exists"}
 
 
@@ -512,6 +519,7 @@ async def mark_item(item_id: int, current_user: User = Depends(get_current_activ
     cursor = conn.cursor()
     cursor.execute("UPDATE items SET marked = NOT marked WHERE id = ?", (item_id,))
     conn.commit()
+    await manager.broadcast_update()
     conn.close()
     return {"status": "ok"}
 
@@ -538,6 +546,7 @@ async def delete_marked_items(request: Optional[DeletionRequest] = None, current
     cursor = conn.cursor()
     cursor.execute("DELETE FROM items WHERE marked = 1")
     conn.commit()
+    await manager.broadcast_update()
     conn.close()
     return {"status": "ok"}
 
@@ -585,6 +594,7 @@ async def delete_item(item_id: int, current_user: User = Depends(get_current_act
     cursor.execute("DELETE FROM items WHERE id = ?", (item_id,))
     conn.commit()
     conn.close()
+    await manager.broadcast_update()
     return {"status": "ok"}
 
 

static/index.html

@@ -493,6 +493,8 @@
                     } else {
                         onlineUsersContainer.style.display = 'none';
                     }
+                } else if (data.type === 'update') {
+                    fetchItems();
                 }
             };