Why i take an exception with my endpoint fastapi?

I have got an db like:

class NewsBase(BaseModel):
    title: str
    topic: str


class NewsCreate(NewsBase):
    datetime: datetime


class News(NewsBase):
    id: int
    datetime: datetime

    class Config:
        orm_mode = True

When i try to make this request, it returns with 500:

@app.get("/news/find_by_topic/{topic}", response_model=schemas.News)
def find_news_by_topic(topic: str, db: Session = Depends(get_db)):
    db_news = crud.get_news_by_topic(db, topic=topic)
    if db_news is None:
        raise HTTPException(status_code=404, detail="This title is not found")
    return db_news

Crud.py:

def get_news_by_topic(db: Session, topic: str):
    return db.query(models.News).filter(models.News.topic == topic).all()

It's like error:

 File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\middleware\errors.py", line 184, in __call__
    raise exc
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\middleware\errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\middleware\exceptions.py", line 79, in __call__
    raise exc
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\middleware\exceptions.py", line 68, in __call__
    await self.app(scope, receive, sender)
  File "C:\Projects\RestAPI\venv\Lib\site-packages\fastapi\middleware\asyncexitstack.py", line 20, in __call__
    raise e
  File "C:\Projects\RestAPI\venv\Lib\site-packages\fastapi\middleware\asyncexitstack.py", line 17, in __call__
    await self.app(scope, receive, send)
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\routing.py", line 718, in __call__
    await route.handle(scope, receive, send)
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "C:\Projects\RestAPI\venv\Lib\site-packages\starlette\routing.py", line 66, in app
    response = await func(request)
               ^^^^^^^^^^^^^^^^^^^
  File "C:\Projects\RestAPI\venv\Lib\site-packages\fastapi\routing.py", line 291, in app
    content = await serialize_response(
              ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Projects\RestAPI\venv\Lib\site-packages\fastapi\routing.py", line 154, in serialize_response
    raise ResponseValidationError(
fastapi.exceptions.ResponseValidationError

How can I fix it?

It seems like you need to set response_model properly. Read more here.

If you are using Python 3.9:

response_model=list[schemas.News]

If you are using older Python:

from typing import List

response_model=List[schemas.News]