FastAPI无法将SQLModel模型作为路由返回类型的问题求助

我最近在跟着FastAPI的文档开发API，文档里用SQLModel定义了Hero模型，还说明这个模型本质上就是一个Pydantic模型，可以直接用作路由的返回类型。不过我发现文档里的@app.on_event("startup")装饰器已经过时了，按照编辑器提示换成了lifespan事件。

但当我照着文档的写法，把Hero模型作为路由返回类型时，Python抛出了如下错误：

fastapi.exceptions.FastAPIError: Invalid args for response field! Hint: check that <module 'models.Hero' from 'C:...\Hero.py'> is a valid Pydantic field type. If you are using a return type annotation that is not a valid Pydantic field (e.g. Union[Response, dict, None]) you can disable generating the response model from the type annotation with the path operation decorator parameter response_model=None. Read more: https://fastapi.tiangolo.com/tutorial/response-model/

我的项目结构如下：

src
├── app.py
├── models
│   └── Hero.py
└── service
    └── db_config.py

启动API使用的命令是：

$ uvicorn app:app --reload --host 0.0.0.0 --port 8080

以下是各个文件的代码：

app.py #

from fastapi import FastAPI, Query
from typing import Annotated
from fastapi.responses import JSONResponse
from service.db_config import engine, SessionDep, create_db_and_tables
from contextlib import asynccontextmanager
from sqlmodel import select
from models import Hero

@asynccontextmanager
async def lifespan(app: FastAPI):
    print("Startup")
    create_db_and_tables()
    yield
    print("Shutdown")

app = FastAPI(lifespan=lifespan)

@app.get("/")
def get_welcome_message():
    return JSONResponse(
        content={
            "message": "Welcome to my API"
        },
        status_code=200
    )

@app.post("/heroes")
def create_hero(hero: Hero, session: SessionDep) -> Hero:
    session.add(hero)
    session.commit()
    session.refresh(hero)
    
    return JSONResponse(
        content=hero,
        status_code=200
    )

@app.get("/heroes")
def get_heroes(session: SessionDep, offset: int = 0, limit: Annotated[int, Query(le=100)] = 100) -> list[Hero]:
    heroes = session.exec(select(Hero).offset(offset).limit(limit)).all()
    
    return JSONResponse(
        content=heroes,
        status_code=200
    )

db_config.py #

from typing import Annotated

from fastapi import Depends
from sqlmodel import Session, create_engine, SQLModel

def get_session():
    with Session(engine) as session:
        yield session
        
def create_db_and_tables():
    SQLModel.metadata.create_all(engine)

db_engine = "postgresql"
db_user = "postgresql"
db_user_password = "ADMIN"
db_address = "127.0.0.1"
db_name = "realm"
connect_args = {"check_same_thread": False}
db_url = f"{db_engine}://{db_user}:{db_user_password}@{db_address}/{db_name}"

engine = create_engine(url=db_url, connect_args=connect_args)
SessionDep = Annotated[Session, Depends(get_session)]

Hero.py #

from sqlmodel import Field, SQLModel,table

class Hero(SQLModel, table=True):
    id: str = Field(primary_key=True, nullable=False)
    name: str = Field(nullable=False)
    age: int = Field(nullable=False)

请问我该如何解决这个问题呢？

备注：内容来源于stack exchange，提问作者Benevos