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Server-Sent Events in FastAPI with async Redis Pub/Sub
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| from aioredis import Channel, Redis | |
| from fastapi import FastAPI | |
| from fastapi.params import Depends | |
| from fastapi_plugins import depends_redis, redis_plugin | |
| from sse_starlette.sse import EventSourceResponse | |
| from starlette.responses import HTMLResponse | |
| html = """ | |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>SSE</title> | |
| </head> | |
| <body> | |
| <script> | |
| const evtSource = new EventSource("http://localhost:8000/sse/stream"); | |
| evtSource.addEventListener("message", function(event) { | |
| // Logic to handle status updates | |
| console.log(event.data) | |
| }); | |
| </script> | |
| </body> | |
| </html> | |
| """ | |
| app = FastAPI() | |
| @app.on_event("startup") | |
| async def on_startup() -> None: | |
| await redis_plugin.init_app(app) | |
| await redis_plugin.init() | |
| @app.on_event("shutdown") | |
| async def on_shutdown() -> None: | |
| await redis_plugin.terminate() | |
| @app.get("/sse/demo") | |
| async def get(): | |
| return HTMLResponse(html) | |
| @app.get("/sse/publish") | |
| async def get(channel: str = "default", redis: Redis = Depends(depends_redis)): | |
| await redis.publish(channel=channel, message="Hello world!") | |
| return "" | |
| @app.get("/sse/stream") | |
| async def stream(channel: str = "default", redis: Redis = Depends(depends_redis)): | |
| return EventSourceResponse(subscribe(channel, redis)) | |
| async def subscribe(channel: str, redis: Redis): | |
| (channel_subscription,) = await redis.subscribe(channel=Channel(channel, False)) | |
| while await channel_subscription.wait_message(): | |
| yield {"event": "message", "data": await channel_subscription.get()} |
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