FastAPI server defined on a class

class_fastapi_app.py

# Sometimes you want to define your FastAPI app within a class for some reason, e.g., 
# you wanted to initialize the servers at the point you intended, not the point of import.
#
# In this case, @app.method decorator doesn't work as-is with instance methods due to the
# difference of its signature.
#
# You need to manually call the decorator as a usual function after obtaining self (e.g.,
# in the __init__ method like below) rather than using the decorator syntax.

class MyApp:
    def __init__(self):
        self._app = fastapi.FastAPI()
        self._app.get("/hello")(self._hello)  # Functional form to register the endpoint.

    @property
    def app(self) -> fastapi.FastAPI:
        return self._app

    async def _hello(self):
        return {"hello": "world"}


if __name__ == "__main__":
    # Obtains the ASGI interface of your app to pass it to the server process.
    run_your_asgi_server(MyApp().app)