Fastapi: [QUESTION] how can I remove the media type from the main response

[mdbug]

Description

How can I remove the media type from the main response?

@router.delete("/topics/{topic}",
               summary="Delete topic",
               response_class=None,
               responses={
                   200: {"description": "Topic successfully deleted"},
                   404: {"description": "Topic not found"}
               })
async def delete_topic(topic):
    """
    Delete a topic with all of it's entries
    """
    deleted = await delete_topic(topic)
    if not deleted:
        return Response(status_code=404)

    return

In this example the open-api documentation will show no media type for the 404 response, but it will show application/json for the 200 response. How can I remove that. My response body is always empty.

[euri10]

When you return, implicitly you return None and FastAPI under the hood generates a JSONResponse by default.

Should you want to return nothing you have to explicitly specify it using Response(status_code=whatever status you want)

see also https://github.com/tiangolo/fastapi/issues/449 for alternatives, in particular @dmontagu's one using the decorator

[mdbug]

Thank you for your answer. But if I do it like this

@router.delete("/topics/{topic}",
               summary="Delete topic",
               response_class=None,
               responses={
                   200: {"description": "Topic successfully deleted"},
                   404: {"description": "Topic not found"}
               })
async def delete_topic(topic, redis: Redis = Depends(get_redis)):
    """
    Delete a topic with all of it's entries
    """
    deleted = await redis.delete(get_topic_stream_key(topic))
    if deleted == 0:
        return Response(status_code=404)

    return Response(status_code=200)

the documentaion still shows

And if I change response_class to response_class=Response I get "AssertionError: A response class with media_type is needed to generate OpenAPI"

[danielgtaylor]

Confirmed. The OpenAPI output is broken for 204 responses and the workaround mentioned above no longer works to return a blank body. Looks like a bug to me.

[tiangolo]

You now can use response_class=Response, I'm not sure since which version :shrug: (we are now on version 0.54.1).

But this seems to work as you expected:

from fastapi import FastAPI, Response

app = FastAPI()


@app.delete(
    "/topics/{topic}",
    summary="Delete topic",
    response_class=Response,
    responses={
        200: {"description": "Topic successfully deleted"},
        404: {"description": "Topic not found"},
    },
)
async def delete_topic(topic: str):
    """
    Delete a topic with all of it's entries
    """
    return Response(status_code=200)

[mdbug]

thanks