fastapi (starlette) RedirectResponse 重定向到 post 而不是 get 方法

Question

我在返回 RedirectResponse 对象后遇到了奇怪的重定向行为

events.py

router = APIRouter()

@router.post('/create', response_model=EventBase)
async def event_create(
        request: Request,
        user_id: str = Depends(get_current_user),
        service: EventsService = Depends(),
        form: EventForm = Depends(EventForm.as_form)
):
    event = await service.post(
       ...
   )
    redirect_url = request.url_for('get_event', **{'pk': event['id']})
    return RedirectResponse(redirect_url)


@router.get('/{pk}', response_model=EventSingle)
async def get_event(
        request: Request,
        pk: int,
        service: EventsService = Depends()
):
    ....some logic....
    return templates.TemplateResponse(
        'event.html',
        context=
        {
            ...
        }
    )

routers.py

api_router = APIRouter()

...
api_router.include_router(events.router, prefix="/event")

这段代码returns结果

127.0.0.1:37772 - "POST /event/22 HTTP/1.1" 405 Method Not Allowed

好的，我看到出于某种原因调用了 POST 请求而不是 GET 请求。我搜索解释并发现 RedirectResponse 对象默认为代码 307 并调用 POST

我听从建议并添加状态

redirect_url = request.url_for('get_event', **{'pk': event['id']}, status_code=status.HTTP_302_FOUND)

并得到

starlette.routing.NoMatchFound

为了实验，我将 @router.get('/{pk}', response_model=EventSingle) 更改为 @router.post('/{pk}', response_model=EventSingle)

并且重定向成功完成，但是 post 请求不适合我这里。我做错了什么？

UPD

html 形式运行 event/create 逻辑

base.html

<form action="{{ url_for('event_create')}}" method="POST">
...
</form>

base_view.py

@router.get('/', response_class=HTMLResponse)
async def main_page(request: Request,
                    activity_service: ActivityService = Depends()):
    activity = await activity_service.get()
    return templates.TemplateResponse('base.html', context={'request': request,
                                                            'activities': activity})

Answer 1

如果您想在 POST 之后重定向到 GET，最佳做法是 to redirect with a 303 status code，因此只需将您的代码更新为：

    # ...
    return RedirectResponse(redirect_url, status_code=303)

如您所见，redirecting with 307 keeps the HTTP method and body。

完整的工作示例：

from fastapi import FastAPI, APIRouter, Request
from fastapi.responses import RedirectResponse, HTMLResponse


router = APIRouter()

@router.get('/form')
def form():
    return HTMLResponse("""
    <html>
    <form action="/event/create" method="POST">
    <button>Send request</button>
    </form>
    </html>
    """)

@router.post('/create')
async def event_create(
        request: Request
):
    event = {"id": 123}
    redirect_url = request.url_for('get_event', **{'pk': event['id']})
    return RedirectResponse(redirect_url, status_code=303)


@router.get('/{pk}')
async def get_event(
        request: Request,
        pk: int,
):
    return f'<html>oi pk={pk}</html>'

app = FastAPI(title='Test API')

app.include_router(router, prefix="/event")

到运行，安装 pip install fastapi uvicorn 和运行：

uvicorn --reload --host 0.0.0.0 --port 3000 example:app

然后，将浏览器指向：http://localhost:3000/event/form

Answer 2

您向 is returned as you are trying to access the event_create endpoint via http://127.0.0.1:8000/event/create, for instance. However, since event_create route handles POST requests, your request ends up in get_event endpoint (and returns a value is not a valid integer error, since you are passing a string instead of integer), as when you type a URL in the address bar of your browser, it performs a GET request. Thus, you need a form, for example, to submit a POST request to the event_create endpoint. Below is an example, similar to the one provided by @Elias Dorneles, which you can run, for example on port 8000, and access the form at http://127.0.0.1:8000/event/ to send a POST request, which will then lead to the RedirectResponse. As @tiangolo posted here, when performing a RedirectResponse from a POST request route to GET request route, the response status code has to change提到status_code=status.HTTP_303_SEE_OTHER的错误。

from fastapi import APIRouter, FastAPI, Request, status
from fastapi.responses import RedirectResponse, HTMLResponse

router = APIRouter()

# Endpoint can be accessed at http://127.0.0.1:8000/event/
@router.get('/', response_class=HTMLResponse)
async def event_create_form(request: Request):
    html_content = """
    <html>
       <body>
          <h1>Create an event</h1>
          <form method="POST" action="/event/create">
             <input type="submit" value="Create Event">
          </form>
       </body>
    </html>
    """
    return HTMLResponse(content=html_content, status_code=200)
    
@router.post('/create')
async def event_create(request: Request):
    event = {"id": 1}
    redirect_url = request.url_for('get_event', **{'pk': event['id']})
    return RedirectResponse(redirect_url, status_code=status.HTTP_303_SEE_OTHER)    

@router.get('/{pk}')
async def get_event(request: Request, pk: int):
    return {"pk": pk}


app = FastAPI()
app.include_router(router, prefix="/event")

fastapi (starlette) RedirectResponse 重定向到 post 而不是 get 方法

fastapi (starlette) RedirectResponse redirect to post instead get method

python

starlette

fastapi

完整的工作示例：