FastAPI default response for specific status

Question

here we can declare what status code should be sent to client when the endpoint is called:

@router.post("/", status_code=status.HTTP_201_CREATED)

the problem I faced for a response body I must return some something be it a JSONResponse or PlainTextResponse and I wonder if it’s possible to not return anything in the router body, but define a default behavior and response for any status code like this for example:

@router.post("/", status_code=status.HTTP_201_CREATED)
async def create_post(req: post_schemas.Post):
    # create the post record
    # I wanna get rid of this part and do this automatically in a way
    return PlainTextResponse(status_code=status.HTTP_201_CREATED, content="Created")

and the client gets "Created" message instead of null

EDIT
This is what I came up with

responses = {200: "OK", 201: "Created"}

@app.middleware("http")
async def no_response_middleware(request: Request, call_next):
    response = await call_next(request)
    if (
        response.status_code in responses
        and int(response.headers["content-length"]) == 4
    ):
        return PlainTextResponse(
            status_code=response.status_code, content=responses.get(response.status_code)
        )
    return response

Asked By: Hossein Gholami

||

Source

Answer 1

It’s doable with middleware

It can get access to the response before it’s returned to the client. Meaning you can write custom logic there and replace it if needed

@app.middleware("http")
async def no_response_middleware(request: Request, call_next):
    response = await call_next(request)
    if is_null_response(response) and response.status_code == 201: # Maybe just a check for 201
        return MyDefaultResponse
    return response

Answered By: Stepan Filonov

FastAPI default response for specific status

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