I have an endpoint in my python fast api and whenver the frontend connects to it, I want to listen for changes on a specific file stored in the temporary directory of the system. I am using watch dog, but I am not able to make it work it, its just not sending any message on changes :-

class LogFileEventHandler(FileSystemEventHandler):
    def __init__(self, websocket: WebSocket, videoId: str):
        self.websocket = websocket
        self.videoId = videoId

    async def on_modified(self, event):
        if event.src_path.endswith(f"log_{self.videoId}.txt"):
            logFile = os.path.join(temp_dir, f"log_{self.videoId}.txt")
            with open(logFile, "r") as file:
                content = file.read()
                # Send file content to WebSocket
                await self.websocket.send_text(content)

@router.websocket("/logs")
async def websocket_endpoint(websocket: WebSocket, videoId: str = Query(...)):
    await manager.connect(websocket)

    print(f" Client connected: {websocket.client.host}")
 
    # Create event handler and observer
    event_handler = LogFileEventHandler(websocket, videoId)
    observer = Observer()
    observer.schedule(event_handler, temp_dir, recursive=False)
    observer.start()

    try:
        while True:
            try:
                data = await websocket.receive_json()
            except RuntimeError:
                break  
    except WebSocketDisconnect:
        print(f"Client disconnected: {websocket.client.host}") 
        manager.disconnect(websocket)
        observer.stop()
        observer.join()