실시간 채팅 애플리케이션 만들기
FastAPI에서 WebSocket 기능을 보여 주는 간단한 실시간 채팅 애플리케이션을 개발합니다.
실시간 채팅 애플리케이션 만들기은(는) CoddyKit의 무료 FastAPI Backend Development Bootcamp 강의입니다. 이것은 4개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 FastAPI Backend Development Bootcamp 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. FastAPI Backend Development Bootcamp 강의에는 총 4개의 강의가 포함되어 있습니다.
이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.
Real-time Chat App Overview
Welcome to building your very own real-time chat application! This lesson brings together everything we've learned about WebSockets in FastAPI.
- We'll create a FastAPI server that manages multiple chat connections.
- Clients will connect via WebSockets to send and receive messages instantly.
- You'll see both the server-side (FastAPI) and a simple client-side (HTML/JavaScript) implementation.
Get ready to see real-time communication in action!
Managing Chat Connections
For a chat application, our server needs to keep track of all active WebSocket connections. When a user sends a message, the server will broadcast it to everyone else.
We'll use a simple ConnectionManager class to handle adding, removing, and broadcasting messages to connected clients.
from typing import List
from fastapi import WebSocket
class ConnectionManager:
def __init__(self):
self.active_connections: List[WebSocket] = []
async def connect(self, websocket: WebSocket):
await websocket.accept()
self.active_connections.append(websocket)
def disconnect(self, websocket: WebSocket):
self.active_connections.remove(websocket)
async def send_personal_message(self, message: str, websocket: WebSocket):
await websocket.send_text(message)
async def broadcast(self, message: str):
for connection in self.active_connections:
await connection.send_text(message)FastAPI WebSocket Endpoint
Now let's create the FastAPI endpoint that clients will connect to. This endpoint will use our ConnectionManager.
When a client connects, we add them. When they send a message, we broadcast it. If they disconnect, we remove them.
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
# ... ConnectionManager class from previous scene ...
app = FastAPI()
manager = ConnectionManager()
@app.websocket("/ws/{client_id}")
async def websocket_endpoint(websocket: WebSocket, client_id: int):
await manager.connect(websocket)
try:
while True:
data = await websocket.receive_text()
message = f"Client #{client_id} says: {data}"
await manager.broadcast(message)
except WebSocketDisconnect:
manager.disconnect(websocket)
await manager.broadcast(f"Client #{client_id} left the chat")Client-Side HTML Structure
Our chat application needs a simple user interface. We'll use basic HTML for an input field to send messages and a div to display them.
This is the foundation for our client-side interaction.
<!DOCTYPE html>
<html>
<head>
<title>Chat App</title>
</head>
<body>
<h1>FastAPI Chat</h1>
<form action="" onsubmit="sendMessage(event)">
<input type="text" id="messageText" autocomplete="off"/>
<button>Send</button>
</form>
<ul id='messages'>
</ul>
</body>
</html>Connecting with JavaScript
Now, let's add JavaScript to our HTML to connect to the FastAPI WebSocket server. We'll open a connection as soon as the page loads.
Remember to replace localhost:8000 with your server address if it's different!
<script>
var ws = new WebSocket("ws://localhost:8000/ws/1");
ws.onopen = function(event) {
console.log("Connected to WebSocket server!");
};
ws.onclose = function(event) {
console.log("Disconnected from WebSocket server.");
};
ws.onerror = function(error) {
console.error("WebSocket Error: ", error);
};
</script>Sending Messages from Client
Users need to be able to type a message and send it to the server. We'll create a JavaScript function that captures the input and sends it via the WebSocket connection.
This function is called when the form is submitted.
<script>
// ... WebSocket connection setup ...
function sendMessage(event) {
var input = document.getElementById("messageText");
ws.send(input.value);
input.value = '';
event.preventDefault();
}
</script>Receiving & Displaying Messages
The core of a chat application is receiving messages and displaying them. We'll implement the ws.onmessage event handler to append new messages to our list.
<script>
// ... WebSocket connection & sendMessage function ...
ws.onmessage = function(event) {
var messages = document.getElementById('messages');
var message = document.createElement('li');
var content = document.createTextNode(event.data);
message.appendChild(content);
messages.appendChild(message);
};
</script>Full FastAPI Chat Server
Here's the complete Python code for our FastAPI chat server. Save this as main.py and run it using uvicorn main:app --reload.
This server will listen for connections, broadcast messages, and announce user joins/leaves.
from typing import List
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from fastapi.responses import HTMLResponse
class ConnectionManager:
def __init__(self):
self.active_connections: List[WebSocket] = []
async def connect(self, websocket: WebSocket):
await websocket.accept()
self.active_connections.append(websocket)
def disconnect(self, websocket: WebSocket):
self.active_connections.remove(websocket)
async def broadcast(self, message: str):
for connection in self.active_connections:
await connection.send_text(message)
app = FastAPI()
manager = ConnectionManager()
html = """
<!DOCTYPE html>
<html>
<head>
<title>Chat App</title>
</head>
<body>
<h1>FastAPI Chat</h1>
<form action="" onsubmit="sendMessage(event)">
<input type="text" id="messageText" autocomplete="off"/>
<button>Send</button>
</form>
<ul id='messages'>
</ul>
<script>
var ws = new WebSocket("ws://localhost:8000/ws/1"); // Client ID is 1 for this example
ws.onopen = function(event) {
console.log("Connected to WebSocket server!");
};
ws.onmessage = function(event) {
var messages = document.getElementById('messages');
var message = document.createElement('li');
var content = document.createTextNode(event.data);
message.appendChild(content);
messages.appendChild(message);
};
ws.onclose = function(event) {
console.log("Disconnected from WebSocket server.");
};
ws.onerror = function(error) {
console.error("WebSocket Error: ", error);
};
function sendMessage(event) {
var input = document.getElementById("messageText");
ws.send(input.value);
input.value = '';
event.preventDefault();
}
</script>
</body>
</html>
"""
@app.get("/")
async def get():
return HTMLResponse(html)
@app.websocket("/ws/{client_id}")
async def websocket_endpoint(websocket: WebSocket, client_id: int):
await manager.connect(websocket)
await manager.broadcast(f"Client #{client_id} joined the chat")
try:
while True:
data = await websocket.receive_text()
message = f"Client #{client_id} says: {data}"
await manager.broadcast(message)
except WebSocketDisconnect:
manager.disconnect(websocket)
await manager.broadcast(f"Client #{client_id} left the chat")Quick Chat Logic Check
You've built a basic chat app! Consider the ConnectionManager's broadcast method and the FastAPI endpoint's logic.
If Client A sends a message to the server, what happens next to ensure Client B receives it?
Chat App Summary
Congratulations! You've successfully built a basic real-time chat application using FastAPI WebSockets.
- You learned to manage multiple active WebSocket connections with a
ConnectionManager. - You implemented a FastAPI WebSocket endpoint to handle incoming and outgoing messages.
- You created a simple HTML/JavaScript client to connect, send, and receive chat messages.
This project demonstrates the power of WebSockets for real-time communication. From here, you can add features like user authentication, persistent chat history, and more robust UI/UX.
AI 튜터와 함께 FastAPI Backend Development Bootcamp을(를) 배우세요 — 무료
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“실시간 채팅 애플리케이션 만들기” 강의는 무료인가요?
네 — “실시간 채팅 애플리케이션 만들기” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 FastAPI Backend Development Bootcamp 강의 전체를 잠금 해제할 수 있습니다. FastAPI Backend Development Bootcamp 강의에는 총 4개의 강의가 포함되어 있습니다.
“실시간 채팅 애플리케이션 만들기”에서 뭘 배우나요?
FastAPI에서 WebSocket 기능을 보여 주는 간단한 실시간 채팅 애플리케이션을 개발합니다. 브라우저에서 직접 실행하는 실습 코드로 FastAPI Backend Development Bootcamp을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.
FastAPI Backend Development Bootcamp을(를) 시작하는 데 경험이 필요한가요?
사전 경험은 필요하지 않습니다. CoddyKit의 FastAPI Backend Development Bootcamp은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 3번째 강의입니다.
“실시간 채팅 애플리케이션 만들기” 강의는 얼마나 걸리나요?
대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.
이 FastAPI Backend Development Bootcamp 강의에서 코드를 작성하고 실행할 수 있나요?
네. 모든 FastAPI Backend Development Bootcamp 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.