Fastapi help needed - event system

app.py

import dataclasses
import logging
from typing import Annotated, Callable, Dict, List

from fastapi import Depends, FastAPI

logger = logging.getLogger(__name__)


class EventsCollection():

    def __init__(self):
        self.events: Dict[str, List[Callable]] = {}

    def register(self, event, listener):
        event_name = f"{event.__module__}.{event.__name__}"

        logger.warning(f"registering event [{event_name}] with listener [{str(listener)}]")

        self.events.setdefault(event_name, [])
        self.events[event_name].append(listener)

    async def dispatch(self, event):
        event_name = f"{event.__module__}.{event.__class__.__name__}"
        logger.warning(f"dispatching event [{event_name}]")
        listeners = self.events.get(event_name, None)
        if listeners:
            for listener in listeners:
                # listener needs to be able to request whatever defined dependency there is here like DB / user / request etc as well as pasing the event object through
                await listener(event)


events = EventsCollection()


#
#
# Events = Annotated[EventsCollection, Depends(events)]

# want to pass this event via dispatch
@dataclasses.dataclass
class BasicEvent:
    bird: str
    owl: str


# want this to be looked up in the listener for the event
@dataclasses.dataclass
class ListenerDependency:
    dog: str
    cat: str


# defining the listeners dependency
async def basic_dependency():
    return ListenerDependency(
        dog="woof",
        cat="meow"
    )


BasicDependency = Annotated[ListenerDependency, Depends(basic_dependency)]


# the listener
async def listener(event, dep: BasicDependency):
    print("LISTENER CALLED")
    print(event)
    print(dep)

# registering the event
events.register(BasicEvent, listener)

app = FastAPI()


# works but no event
@app.get("/")
async def testing(dep: BasicDependency):
    print(dep)
    # ListenerDependency(dog='woof', cat='meow')


# want this to work
@app.get("/")
async def testing(events: Events):
    event = BasicEvent(
        bird="squeak",
        owl="hiss"
    )
    events.dispatch(event)
    # desired
    # BasicEvent(bird='squeak',owl='hiss')
    # ListenerDependency(dog='woof', cat='meow')
    #
    # since the event got dispatched, so the listener outputs the event, and then its own defined dependency
    # the idea here is that i only need to pass events to the service layer instead of every single possible dependency there might be, user / db / request etc