为什么TypeError：'_PoolContextManager'对象不可迭代

Question

我尝试学习aiohttp，但是peewee-async / aiopg出现了问题

import settings
import jinja2
import aiohttp_jinja2
import peewee
import logging
from peewee_async import Manager, PostgresqlDatabase
from aiohttp import web

logging.basicConfig(level=logging.DEBUG)

database = PostgresqlDatabase(
    settings.DB_NAME,
    user=settings.DB_USER,
    password=settings.DB_PASSWORD,
    host=settings.DB_HOST
)

routes = web.RouteTableDef()


class UserModel(peewee.Model):

    role_choices = (
        (0, "User"),
        (1, "Admin")
    )
    sex_choices = (
        (0, "Male"),
        (1, "Female")
    )

    id = peewee.PrimaryKeyField(
        null=True
    )
    username = peewee.CharField(
        max_length=255
    )
    email = peewee.CharField(
        max_length=255,
        unique=True,
        constraints=[peewee.Check("email ~* '^[A-Za-z0-9._-]+@[A-Za-z0-9.-]+[.][A-Za-z]+$'")],
        index=True
    )
    role = peewee.SmallIntegerField(
        choices=role_choices,
        default=0
    )
    password = peewee.CharField(
        max_length=255
    )
    sex = peewee.SmallIntegerField(
        null=True,
        choices=sex_choices
    )
    age = peewee.SmallIntegerField(
        null=True
    )

    class Meta:
        database = database


@routes.get('/')
async def hello(request):
    await request.app.objects.create(
        UserModel,
        username="admin",
        email="admin@admin.com",
        role=1,
        password="admin123",
        sex=0,
        age=26
    )
    user = await request.app.objects.get(UserModel, email="admin@admin.com")
    context = {'user': user}
    response = aiohttp_jinja2.render_template('base.html',
                                              request,
                                              context)
    response.headers['Content-Language'] = 'ru'
    return response


if __name__ == '__main__':
    app = web.Application()
    app.add_routes(routes)
    app.database = database
    app.database.set_allow_sync(False)
    app.objects = Manager(app.database)
    #database.create_table(UserModel)
    aiohttp_jinja2.setup(app,
                         loader=jinja2.FileSystemLoader(settings.TEMPLATE_DIR))
    web.run_app(app, host=settings.HOST, port=settings.PORT)

当我切换到“ localhost”时发生错误。在对数据库的任何请求阶段，无论是创建还是选择。肯定有到数据库的连接，我创建了一个表并尝试从pg_catalog中进行选择。错误文字：

^Croot@933eff50aca7:/app# python main.py
DEBUG:asyncio:Using selector: EpollSelector
======== Running on http://0.0.0.0:80 ========
(Press CTRL+C to quit)
DEBUG:peewee.async:('INSERT INTO "usermodel" ("username", "email", "role", "password", "sex", "age") VALUES (%s, %s, %s, %s, %s, %s
) RETURNING "id"', (['admin', 'admin@admin.com', 1, 'admin123', 0, 26],), {})
/usr/local/lib/python3.7/site-packages/peewee_async.py:1078: RuntimeWarning: coroutine 'Pool.from_pool_fill' was never awaited
  **self.connect_kwargs)
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
ERROR:aiohttp.server:Error handling request
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/aiohttp/web_protocol.py", line 418, in start
    resp = await task
  File "/usr/local/lib/python3.7/site-packages/aiohttp/web_app.py", line 458, in _handle
    resp = await handler(request)
  File "main.py", line 73, in hello
    age=26
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 181, in create
    pk = yield from self.execute(query)
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 269, in execute
    return (yield from execute(query))
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 433, in execute
    return (yield from coroutine(query))
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 597, in insert
    cursor = yield from _execute_query_async(query)
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 1558, in _execute_query_async
    return (yield from _run_sql(query.database, *query.sql()))
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 1537, in _run_sql
    cursor = yield from database.cursor_async()
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 921, in cursor_async
    yield from self.connect_async(loop=self._loop)
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 907, in connect_async
    yield from conn.connect()
  File "/usr/local/lib/python3.7/site-packages/peewee_async.py", line 1078, in connect
    **self.connect_kwargs)
TypeError: '_PoolContextManager' object is not iterable

使用docker-compose。软件包版本：

aiodns==2.0.0
aiohttp==3.6.2
aiohttp-jinja2==1.2.0
aiopg==1.0.0
async-timeout==3.0.1
attrs==19.3.0
cchardet==2.1.5
certifi==2019.11.28
cffi==1.13.2
chardet==3.0.4
idna==2.8
Jinja2==2.10.3
MarkupSafe==1.1.1
multidict==4.7.1
peewee==2.10.2
peewee-async==0.5.12
pipenv==2018.10.13
psycopg2-binary==2.8.4
pycares==3.1.0
pycparser==2.19
virtualenv==16.7.9
virtualenv-clone==0.5.3
yarl==1.4.2