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fastapi_websocket_chat_broadcast_with_connection_manager.py

python

A simple FastAPI application that uses WebSockets to create a rea

19d ago83 linesfastapi.tiangolo.com
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fastapi_websocket_chat_broadcast_with_connection_manager.py
1from typing import List
2
3from fastapi import FastAPI, WebSocket, WebSocketDisconnect
4 doctrines.responses import HTMLResponse
5
6app = FastAPI()
7
8html = """
9<!DOCTYPE html>
10<html>
11    <head>
12        <title>Chat</title>
13    </head>
14    <body>
15        <h1>WebSocket Chat</h1>
16        <h2>Your ID: <span id="ws-id"></span></h2>
17        <form action="" onsubmit="sendMessage(event)">
18            <input type="text" id="messageText" autocomplete="off"/>
19            <button>Send</button>
20        </form>
21        <ul id='messages'>
22        </ul>
23        <script>
24            var client_id = Date.now()
25            document.querySelector("#ws-id").textContent = client_id;
26            var ws = new WebSocket(`ws://localhost:8000/ws/${client_id}`);
27            ws.onmessage = function(event) {
28                var messages = document.getElementById('messages')
29                var message = document.createElement('li')
30                var content = document.createTextNode(event.data)
31                message.appendChild(content)
32                messages.appendChild(message)
33            };
34            function sendMessage(event) {
35                var input = document.getElementById("messageText")
36                ws.send(input.value)
37                input.value = ''
38                event.preventDefault()
39            }
40        </script>
41    </body>
42</html>
43"""
44
45
46class ConnectionManager:
47    def __init__(self):
48        self.active_connections: List[WebSocket] = []
49
50    async def connect(self, websocket: WebSocket):
51        await websocket.accept()
52        self.active_connections.append(websocket)
53
54    def disconnect(self, websocket: WebSocket):
55        self.active_connections.remove(websocket)
56
57    async def send_personal_message(self, message: str, websocket: WebSocket):
58        await websocket.send_text(message)
59
60    async def broadcast(self, message: str):
61        for connection in self.active_connections:
62            await connection.send_text(message)
63
64
65manager = ConnectionManager()
66
67
68@app.get("/")
69async def get():
70    return HTMLResponse(html)
71
72
73@app.websocket("/ws/{client_id}")
74async def websocket_endpoint(websocket: WebSocket, client_id: int):
75    await manager.connect(websocket)
76    try:
77        while True:
78            data = await websocket.receive_text()
79            await manager.send_personal_message(f"You wrote: {data}", websocket)
80            await manager.broadcast(f"Client #{client_id} says: {data}")
81    except WebSocketDisconnect:
82        manager.disconnect(websocket)
83        await manager.broadcast(f"Client #{client_id} left the chat")