我从TortoiseORM切换到使用SQLAlchemy，并认为我应该研究一下Alembic来处理它的迁移。在编辑了 env.py 和 alembic.ini 文件后，我仍然无法让alembic生成任何迁移。
错误sqlalchemy.exc.MissingGreenlet: greenlet_spawn has not been called; can't call await_only() here. Was IO attempted in an unexpected place? (Background on this error at: https://sqlalche.me/e/14/xd2s) sys:1: RuntimeWarning: coroutine 'connect' was never awaited是不言自明的，但我不知道到底要更改什么。
我按照FastAPI-Users文档中的指示操作，但我完全迷路了。
我尝试过的：

• 将run_migrations_offline()和run_migrations_online()设置为async
• 使用asyncio.run()来运行它们
  models.py

import os
from typing import AsyncGenerator
from fastapi import Depends
from fastapi_users.db import SQLAlchemyBaseUserTableUUID, SQLAlchemyUserDatabase
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import Column, String, Integer, DateTime

DATABASE_URL = os.getenv('DATABASE_URL')
Base: DeclarativeMeta = declarative_base()

class Account(Base):
    __tablename__ = 'app_account'
    id = Column(Integer, primary_key=True, nullable=False)
    timezone = Column(String(5), default='+0800')

engine = create_async_engine(DATABASE_URL)
async_session_maker = sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)

async def create_db_and_tables():
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)                                       # noqa

async def get_async_session() -> AsyncGenerator[AsyncSession, None]:
    async with async_session_maker() as session:
        yield session

缩略语.ini

sqlalchemy.url = postgresql+asyncpg://foo:pass123@127.0.0.1:5432/foo

env.py

# add your model's MetaData object here
# for 'autogenerate' support
from models import Base
target_metadata = Base.metadata

运行alembic revision --autogenerate：

Traceback (most recent call last):
  File "/home/dever/venv/systemapp-ne8n42/bin/alembic", line 8, in <module>
    sys.exit(main())
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/config.py", line 590, in main
    CommandLine(prog=prog).main(argv=argv)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/config.py", line 584, in main
    self.run_cmd(cfg, options)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/config.py", line 561, in run_cmd
    fn(
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/command.py", line 229, in revision
    script_directory.run_env()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/script/base.py", line 569, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/util/pyfiles.py", line 94, in load_python_file
    module = load_module_py(module_id, path)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/alembic/util/pyfiles.py", line 110, in load_module_py
    spec.loader.exec_module(module)  # type: ignore
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "migrations/env.py", line 77, in <module>
    run_migrations_online()
  File "migrations/env.py", line 65, in run_migrations_online
    with connectable.connect() as connection:
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 3234, in connect
    return self._connection_cls(self, close_with_result=close_with_result)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 96, in __init__
    else engine.raw_connection()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 3313, in raw_connection
    return self._wrap_pool_connect(self.pool.connect, _connection)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/base.py", line 3280, in _wrap_pool_connect
    return fn()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 310, in connect
    return _ConnectionFairy._checkout(self)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 868, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 476, in checkout
    rec = pool._do_get()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/impl.py", line 256, in _do_get
    return self._create_connection()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 256, in _create_connection
    return _ConnectionRecord(self)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 371, in __init__
    self.__connect()
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 666, in __connect
    pool.logger.debug("Error on connect(): %s", e)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    compat.raise_(
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/util/compat.py", line 208, in raise_
    raise exception
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/pool/base.py", line 661, in __connect
    self.dbapi_connection = connection = pool._invoke_creator(self)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/create.py", line 590, in connect
    return dialect.connect(*cargs, **cparams)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/engine/default.py", line 597, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 777, in connect
    await_only(self.asyncpg.connect(*arg, **kw)),
  File "/home/dever/venv/systemapp-ne8n42/lib/python3.9/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 59, in await_only
    raise exc.MissingGreenlet(
sqlalchemy.exc.MissingGreenlet: greenlet_spawn has not been called; can't call await_only() here. Was IO attempted in an unexpected place? (Background on this error at: https://sqlalche.me/e/14/xd2s)
sys:1: RuntimeWarning: coroutine 'connect' was never awaited

接下来我可以尝试什么？