Async SQLAlchemy 无法在数据库中创建表

Question

main.py

from fastapi import FastAPI
import uvicorn
from database.connection import init_models

app = FastAPI()

@app.on_event('startup')
async def init_db() -> None:
    await init_models()

if __name__ == '__main__':
    uvicorn.run('main:app', host='0.0.0.0', port=8000, reload=True)

连接.py

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker, AsyncSession
from dotenv import load_dotenv
import os

load_dotenv()

DATABASE_URL: str = f'postgresql+asyncpg://{os.getenv("POSTGRES_USER")}:{os.getenv("POSTGRES_PASSWORD")}@localhost:5432/postgres'
SECRET_KEY: str = os.getenv('SECRET_KEY')

engine = create_async_engine(DATABASE_URL, echo=True)
async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)

Base = declarative_base()

async def init_models() -> None:
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.drop_all)
        await conn.run_sync(Base.metadata.create_all)

async def get_session() -> AsyncSession:
    async with async_session() as session:
        yield session

我得到这样的输出：

INFO:     Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [4529] using StatReload
INFO:     Started server process [4534]
INFO:     Waiting for application startup.
2023-03-14 13:48:57,835 INFO sqlalchemy.engine.Engine select pg_catalog.version()
2023-03-14 13:48:57,835 INFO sqlalchemy.engine.Engine [raw sql] ()
2023-03-14 13:48:57,836 INFO sqlalchemy.engine.Engine select current_schema()
2023-03-14 13:48:57,836 INFO sqlalchemy.engine.Engine [raw sql] ()
2023-03-14 13:48:57,836 INFO sqlalchemy.engine.Engine show standard_conforming_strings
2023-03-14 13:48:57,836 INFO sqlalchemy.engine.Engine [raw sql] ()
2023-03-14 13:48:57,837 INFO sqlalchemy.engine.Engine BEGIN (implicit)
2023-03-14 13:48:57,837 INFO sqlalchemy.engine.Engine COMMIT
INFO:     Application startup complete.

SQLAlchemy 不创建任何表。我尝试使用不异步的普通会话，尝试使用 alembic，但没有任何帮助。模型一切正常，我不明白问题与哪个有关。