How to fix aiopg.sa error?

Question

Python

Hello! I'm studying the official tutorial on aiohttp, there was a problem at the stage of initializing the connection with postgresql,

conf = app['config']['postgres']
    engine = await aiopg.sa.create_engine(
        database=conf['database'],
        user=conf['user'],
        password=conf['password'],
        host=conf['host'],
        port=conf['port'],
        minsize=conf['minsize'],
        maxsize=conf['maxsize'],
    )
    app['db'] = engine

Traceback (most recent call last):
  File "chapi_pools\main.py", line 14, in <module>
    web.run_app(app)
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\web.py", line 419, in run_app
    loop.run_until_complete(_run_app(app,
  File "c:\myprogramm\python\lib\asyncio\base_events.py", line 616, in run_until_complete
    return future.result()
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\web.py", line 305, in _run_app
    await runner.setup()
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\web_runner.py", line 232, in setup
    self._server = await self._make_server()
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\web_runner.py", line 331, in _make_server
    await self._app.startup()
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\web_app.py", line 389, in startup
    await self.on_startup.send(self)
  File "C:\coding\Chapi\env\lib\site-packages\aiohttp\signals.py", line 34, in send
    await receiver(*args, **kwargs)  # type: ignore
  File "C:\coding\Chapi\chapi_pools\db.py", line 46, in init_pg
    engine = await aiopg.sa.create_engine(
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\sa\engine.py", line 69, in _create_engine
    pool = await aiopg.create_pool(
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\pool.py", line 155, in from_pool_fill
    await self._fill_free_pool(False)
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\pool.py", line 193, in _fill_free_pool
    conn = await connect(
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\connection.py", line 38, in connect
    coro = Connection(
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\connection.py", line 92, in __init__
    self._loop.add_reader(self._fileno, self._ready, self._weakref)
  File "c:\myprogramm\python\lib\asyncio\events.py", line 501, in add_reader
    raise NotImplementedError
NotImplementedError
Exception ignored in: <function Connection.__del__ at 0x04077268>
Traceback (most recent call last):
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\connection.py", line 512, in __del__
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\connection.py", line 310, in close
  File "C:\coding\Chapi\env\lib\site-packages\aiopg\connection.py", line 285, in _close
  File "c:\myprogramm\python\lib\asyncio\events.py", line 504, in remove_reader
NotImplementedError:

I can’t even google this problem properly, so I turn to your help, help, please!

Answer 1

Also encountered this error.
Here is a similar question on stackoverflow .
There is a link to a solution there.
It helped me to put two lines in main.py:

# main.py
# ...
import asyncio

asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

app = web.Application()
app['config'] = config
# ...