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"""
Example demonstrating use with the FastAPI web framework.
Requires the "postgresql" service to be running.
To install prerequisites: pip install sqlalchemy asycnpg fastapi uvicorn
To run: uvicorn asgi_fastapi:app
It should print a line on the console on a one-second interval while running a
basic web app at http://localhost:8000.
"""
from __future__ import annotations
from datetime import datetime
from fastapi import FastAPI
from fastapi.middleware import Middleware
from fastapi.requests import Request
from fastapi.responses import PlainTextResponse, Response
from sqlalchemy.ext.asyncio import create_async_engine
from starlette.types import ASGIApp, Receive, Scope, Send
from apscheduler.datastores.async_sqlalchemy import AsyncSQLAlchemyDataStore
from apscheduler.eventbrokers.asyncpg import AsyncpgEventBroker
from apscheduler.schedulers.async_ import AsyncScheduler
from apscheduler.triggers.interval import IntervalTrigger
def tick():
print("Hello, the time is", datetime.now())
class SchedulerMiddleware:
def __init__(
self,
app: ASGIApp,
scheduler: AsyncScheduler,
) -> None:
self.app = app
self.scheduler = scheduler
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
if scope["type"] == "lifespan":
async with self.scheduler:
await self.scheduler.add_schedule(
tick, IntervalTrigger(seconds=1), id="tick"
)
await self.scheduler.start_in_background()
await self.app(scope, receive, send)
else:
await self.app(scope, receive, send)
async def root(request: Request) -> Response:
return PlainTextResponse("Hello, world!")
engine = create_async_engine("postgresql+asyncpg://postgres:secret@localhost/testdb")
data_store = AsyncSQLAlchemyDataStore(engine)
event_broker = AsyncpgEventBroker.from_async_sqla_engine(engine)
scheduler = AsyncScheduler(data_store, event_broker)
middleware = [Middleware(SchedulerMiddleware, scheduler=scheduler)]
app = FastAPI(middleware=middleware)
app.add_api_route("/", root)
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