For @alexted (https://t.me/aiohttp_ru/3955)

sync_to_async.py

"""
My solution

See https://t.me/aiohttp_ru/3955
"""
import asyncio
import json

import aiohttp
from asgiref.sync import sync_to_async


class HttpClient:
    endpoints = {
        'user': 'https://jsonplaceholder.typicode.com/users/{id}/',
    }

    async def __aenter__(self) -> 'HttpClient':
        self._session = aiohttp.ClientSession()
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb) -> None:
        await self._session.close()

    async def fetch_user_data_by_id(self, user_id):
        url = self.endpoints['user'].format(id=user_id)

        async with self._session.get(url) as resp:
            return await resp.json() if resp.status == 200 else {}


async def get_user_info_by_id(user_id, http_client=None):
    http_client = http_client or HttpClient()  # add http_client
    async with http_client:
        user_info = await http_client.fetch_user_data_by_id(user_id)
    return user_info['username']  # change key 'login' -> 'username'


@sync_to_async  # decorate
def get_user_login_from_webtoken_data(payload):
    subject = json.loads(payload['sub'])
    user_id = subject['uid']

    user_login = asyncio.run(get_user_info_by_id(user_id))
    return user_login


def get_user_login_from_sso_data(payload):
    return payload['preferred_username']


# regular function
def get_user_id_from_token_payload(payload):
    try:
        client_login = get_user_login_from_sso_data(payload)
    except KeyError:
        # it will create a new loop for every call
        client_login = asyncio.run(get_user_login_from_webtoken_data(payload))
    return client_login


if __name__ == '__main__':
    async def main(callback):
        payload = {
            # 'preferred_username': 'superuser',
            'sub': '{"uid": 1}',
        }
        return await callback(payload)

    clb = sync_to_async(get_user_id_from_token_payload)
    result = asyncio.run(main(clb))
    print(result)