There is no current event loop in thread 'Thread-1'

I'm very new to python and I'm trying to implement an API for requesting some data from Interactive Brokers Trader Workstation. I'm using Flask and ib_insync.

Here is my code:

import configparser
import json
import logging.config

from flask import Flask
from ib_insync import IB

flask = Flask(__name__)

ib = IB()

config = configparser.ConfigParser()
config.read('settings.ini')

logging.config.fileConfig('logging.conf')
logger = logging.getLogger('ib-custom')


@flask.route('/health', methods=['GET'])
def health():
    return 'OK'


@flask.route('/summary', methods=['GET'])
def account_summary():
    logger.debug('account_summary called')
    summary = ib.accountSummary()
    return json.dumps([ob._asdict() for ob in summary])


if __name__ == '__main__':
    ib.connect('127.0.0.1', 7497, clientId=1)
    logger.info('Application started')
    flask.run(debug=True, use_reloader=False)

It raises the error when I'm trying to execute localhost:5000/summary. Here is the stacktrace:

Traceback (most recent call last):
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/main.py", line 27, in account_summary
    summary = ib.accountSummary()
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/ib_insync/ib.py", line 405, in accountSummary
    return self._run(self.accountSummaryAsync(account))
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/ib_insync/ib.py", line 310, in _run
    return util.run(*awaitables, timeout=self.RequestTimeout)
  File "/Users/irusanov/Projects/PycharmProjects/ib-custom/venv/lib/python3.8/site-packages/ib_insync/util.py", line 291, in run
    loop = asyncio.get_event_loop()
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/asyncio/events.py", line 639, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'Thread-1'.

Why this error appears? How to fix it?

It appears Flask uses its own internal blocking/callback/threaded model and isn't compatible with Asyncio which this project is built on. Source: https://github.com/erdewit/ib_insync/issues/266

Required behaviour could be implemented using another framework instead of Flask. E.g. Quart.

In the case of using Quart, this code could be rewritten:

import asyncio
import configparser
import json
import logging.config
import nest_asyncio

from quart import Quart
from ib_insync import IB, util

nest_asyncio.apply()
qrt = Quart(__name__)

ib = IB()

config = configparser.ConfigParser()
config.read('settings.ini')

logging.config.fileConfig('logging.conf')
logger = logging.getLogger('ib-custom')


@qrt.route('/health', methods=['GET'])
def health():
    return 'OK'


@qrt.route('/summary')
async def summary():
    with await IB().connectAsync() as ibi:
        acct = ibi.managedAccounts()[0]
        summary = ibi.accountSummary(acct)
        await ibi.accountSummaryEvent
        resp = json.dumps(util.tree(summary))
    return resp


@qrt.route('/pnl')
async def pnl():
    with await IB().connectAsync() as ibi:
        acct = ibi.managedAccounts()[0]
        pnl = ibi.reqPnL(acct)
        await ibi.pnlEvent
        resp = json.dumps(util.tree(pnl))
    return resp


if __name__ == '__main__':
    # ib.connect('127.0.0.1', 7497, clientId=1)
    logger.info('Application started')
    qrt.run(debug=True)