A minimal example showing that APIRouter does not support `lifespan`

no_lifespan_on_APIRouter.py

from contextlib import asynccontextmanager

from fastapi import FastAPI, APIRouter


def fake_answer_to_everything_ml_model(x: float):
    return x * 42


ml_models = {}


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Load the ML model
    ml_models["answer_to_everything"] = fake_answer_to_everything_ml_model
    yield
    # Clean up the ML models and release the resources
    ml_models.clear()


app = FastAPI()
router = APIRouter(lifespan=lifespan)

@router.get("/predict")
async def predict(x: float):
    result = ml_models["answer_to_everything"](x)
    return {"result": result}