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WebSockets API

@app.websocket()

Section titled “@app.websocket()”

Register a WebSocket handler:

@app.websocket(path="/ws")
async def handler(ws):
    await ws.accept()
    ...
Parameter Type Default Description
path str required WebSocket endpoint path

WebSocket Object

Section titled “WebSocket Object”
Method Description
await ws.accept() Accept the WebSocket upgrade
await ws.receive_text() Receive a text message (str)
await ws.receive_bytes() Receive a binary message (bytes)
await ws.receive_json() Receive and parse JSON message
await ws.send_text(data) Send a text message
await ws.send_bytes(data) Send a binary message
await ws.send_json(data) Send JSON message
await ws.close() Close the connection

WebSocketState

Section titled “WebSocketState”
State Description
CONNECTING Initial state, waiting for upgrade
OPEN Connection established, messages can be exchanged
CLOSING Close frame sent/received
CLOSED Connection closed

Example

Section titled “Example”
@app.websocket("/chat")
async def chat(ws):
    await ws.accept()
    try:
        while True:
            msg = await ws.receive_text()
            await ws.send_text(f"Echo: {msg}")
    except Exception:
        pass
    finally:
        await ws.close()

See Also

Section titled “See Also”