Scheduled HTTP Request using FastAPI

Question

Inside my FastAPI application, I would like to schedule an HTTP request to be made to check for new results (comparing to database) every X time interval. What would be the easiest way to accomplish this using httpx?

Asked By: apod

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Answer 1

You can add an async task to the event loop during the startup event. This async task would check (and sleep) and store the result somewhere. In the below example, I’ve chosen to pass around a shared object using the app.state feature of FastAPI. This should give you enough pointers to implement your exact use case. I have commented out an example of dealing with https specifically.

from fastapi import FastAPI
import asyncio


class MySharedObject:
    def __init__(self) -> None:
        self.count = 0


async def timed_checker(obj: MySharedObject):
    while True:
        obj.count += 1
        # async with httpx.AsyncClient() as client:
        #    r = await client.get('https://www.example.com/')
        await asyncio.sleep(3)


app = FastAPI()


@app.on_event("startup")
def startup_function():
    app.state.shared_object = MySharedObject()
    asyncio.create_task(timed_checker(app.state.shared_object))


@app.get("/")
async def root():
    return {"hello": "world"}


@app.get("/count")
async def get_count():
    return app.state.shared_object.count


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8000)

Answered By: JarroVGIT

Scheduled HTTP Request using FastAPI

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