How to start background_tasks on event startup

@app.on_event("startup")
async def startup_event(background_tasks: BackgroundTasks):
    send_notification(background_tasks)

2021-05-12 15:31:40,350 - MainThread - ERROR - Traceback (most recent call last):
  File "F:\douyin_spider_fast_api\venv\lib\site-packages\starlette\routing.py", line 540, in lifespan
    async for item in self.lifespan_context(app):
  File "F:\douyin_spider_fast_api\venv\lib\site-packages\starlette\routing.py", line 481, in default_lifespan
    await self.startup()
  File "F:\douyin_spider_fast_api\venv\lib\site-packages\starlette\routing.py", line 516, in startup
    await handler()
TypeError: startup_event() missing 1 required positional argument: 'background_tasks'

[tusharjagtap-bc]

@codemation That is an issue in my opinion. on_event(‘startup’) does not mean that you will always want to call a method without arguments on startup, does it?

In any case, a workaround to be able to start a background task on startup is highly appreciated. I haven’t found a way to do so yet.

[codemation]

The most obvious way to achieve referencing your method that takes arguments, is with a new method with the arguments statically defined:

@app.on_event('startup')
async def startup_event_setup():
    startup_event(background_tasks)

@tusharjagtap-bc It might help if you share what argument that you are passing into your startup event.