MongoDB 集合更新后通过 Socket.IO 自动推送数据到前端 (FastAPI 实现)-优快云博客

MongoDB 集合更新后通过 Socket.IO 自动推送数据到前端 (FastAPI 实现)

要实现 MongoDB 集合更新后自动推送数据到前端的功能，你需要以下几个组件：

MongoDB 变更流 (Change Streams) 监听集合变化
FastAPI 后端处理 WebSocket 连接
Socket.IO 实现实时通信
前端监听 Socket.IO 事件

后端实现 (FastAPI)

首先安装必要的依赖：

pip install fastapi uvicorn motor pymongo python-socketio

1. 创建 FastAPI 应用并设置 MongoDB 连接

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
import socketio
from motor.motor_asyncio import AsyncIOMotorClient
import asyncio

app = FastAPI()

# 设置 CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# MongoDB 配置
MONGO_URL = "mongodb://localhost:27017"
DB_NAME = "your_database"
COLLECTION1 = "collection1"
COLLECTION2 = "collection2"

# 初始化 MongoDB 客户端
mongo_client = AsyncIOMotorClient(MONGO_URL)
db = mongo_client[DB_NAME]

# 初始化 Socket.IO
sio = socketio.AsyncServer(async_mode='asgi', cors_allowed_origins='*')
socket_app = socketio.ASGIApp(sio, app)

2. 设置 MongoDB 变更流监听

async def watch_collection(collection_name):
    collection = db[collection_name]
    async with collection.watch() as stream:
        async for change in stream:
            print(f"Change detected in {collection_name}: {change}")
            # 发送变更通知给所有客户端
            await sio.emit(f"{collection_name}_changed", change)

3. 启动变更流监听任务

@app.on_event("startup")
async def startup_event():
    # 启动两个集合的监听任务
    asyncio.create_task(watch_collection(COLLECTION1))
    asyncio.create_task(watch_collection(COLLECTION2))

4. 设置 Socket.IO 事件处理

@sio.event
async def connect(sid, environ):
    print(f"Client connected: {sid}")

@sio.event
async def disconnect(sid):
    print(f"Client disconnected: {sid}")

5. 运行应用

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(socket_app, host="0.0.0.0", port=8000)

前端实现

前端需要使用 Socket.IO 客户端库来监听后端推送的变更。

HTML/JavaScript 示例

<!DOCTYPE html>
<html>
<head>
    <title>Real-time MongoDB Updates</title>
    <script src="https://cdn.socket.io/4.5.4/socket.io.min.js"></script>
</head>
<body>
    <h1>Real-time Updates</h1>
    <div id="collection1-updates"></div>
    <div id="collection2-updates"></div>

    <script>
        const socket = io('http://localhost:8000');
        
        // 监听集合1的变更
        socket.on('collection1_changed', (data) => {
            console.log('Collection1 changed:', data);
            const div = document.getElementById('collection1-updates');
            div.innerHTML += `<p>${JSON.stringify(data)}</p>`;
        });
        
        // 监听集合2的变更
        socket.on('collection2_changed', (data) => {
            console.log('Collection2 changed:', data);
            const div = document.getElementById('collection2-updates');
            div.innerHTML += `<p>${JSON.stringify(data)}</p>`;
        });
        
        // 连接事件
        socket.on('connect', () => {
            console.log('Connected to server');
        });
        
        // 断开事件
        socket.on('disconnect', () => {
            console.log('Disconnected from server');
        });
    </script>
</body>
</html>

高级配置

1. 过滤变更事件

你可以修改 watch_collection 函数来过滤特定类型的变更：

async def watch_collection(collection_name):
    pipeline = [{
        '$match': {
            '$or': [
                {'operationType': 'insert'},
                {'operationType': 'update'},
                {'operationType': 'replace'},
                {'operationType': 'delete'}
            ]
        }
    }]
    
    collection = db[collection_name]
    async with collection.watch(pipeline=pipeline) as stream:
        async for change in stream:
            print(f"Change detected in {collection_name}: {change}")
            await sio.emit(f"{collection_name}_changed", change)

2. 安全性考虑

添加认证中间件保护 WebSocket 连接
限制可以监听的集合
过滤敏感数据不发送到前端

3. 性能优化

使用批处理发送多个变更
添加速率限制
考虑使用 Redis 作为 Socket.IO 的消息队列

完整示例

完整的后端代码示例：

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
import socketio
from motor.motor_asyncio import AsyncIOMotorClient
import asyncio

app = FastAPI()

# CORS 配置
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# MongoDB 配置
MONGO_URL = "mongodb://localhost:27017"
DB_NAME = "your_database"
COLLECTION1 = "collection1"
COLLECTION2 = "collection2"

# 初始化 MongoDB
mongo_client = AsyncIOMotorClient(MONGO_URL)
db = mongo_client[DB_NAME]

# 初始化 Socket.IO
sio = socketio.AsyncServer(async_mode='asgi', cors_allowed_origins='*')
socket_app = socketio.ASGIApp(sio, app)

async def watch_collection(collection_name):
    """监听 MongoDB 集合变更并广播到客户端"""
    pipeline = [{
        '$match': {
            '$or': [
                {'operationType': 'insert'},
                {'operationType': 'update'},
                {'operationType': 'replace'},
                {'operationType': 'delete'}
            ]
        }
    }]
    
    collection = db[collection_name]
    try:
        async with collection.watch(pipeline=pipeline) as stream:
            print(f"开始监听集合 {collection_name} 的变更...")
            async for change in stream:
                print(f"变更检测于 {collection_name}: {change}")
                # 发送变更到特定房间或所有客户端
                await sio.emit(f"{collection_name}_changed", {
                    "operation": change["operationType"],
                    "data": change.get("fullDocument"),
                    "id": change.get("documentKey", {}).get("_id")
                })
    except Exception as e:
        print(f"监听集合 {collection_name} 时出错: {e}")
        # 出错后重新连接
        await asyncio.sleep(5)
        asyncio.create_task(watch_collection(collection_name))

@app.on_event("startup")
async def startup_event():
    """应用启动时开始监听集合变更"""
    asyncio.create_task(watch_collection(COLLECTION1))
    asyncio.create_task(watch_collection(COLLECTION2))

@sio.event
async def connect(sid, environ):
    """客户端连接事件"""
    print(f"客户端已连接: {sid}")
    await sio.emit("message", {"data": f"欢迎! 你的ID是 {sid}"}, room=sid)

@sio.event
async def disconnect(sid):
    """客户端断开事件"""
    print(f"客户端已断开: {sid}")

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(socket_app, host="0.0.0.0", port=8000)