如何在 FastAPI 请求 header 中限制内容类型

Question

I'm quite new to the FastAPI framework, I want to restrict my request header content type with "application/vnd.api+json", But I can't able to find a way to configure my content type with the Fast API route instance.

Any info will be really useful.

Answer 1

Each request has the content-type in its headers. You could check it like so:

import uvicorn
from fastapi import FastAPI, HTTPException
from starlette import status

from starlette.requests import Request

app = FastAPI()


@app.get("/hello")
async def hello(request: Request):
    content_type = request.headers.get("content-type", None)
    if content_type != "application/vnd.api+json":
        raise HTTPException(
            status_code=status.HTTP_415_UNSUPPORTED_MEDIA_TYPE,
            detail=f"Unsupported media type {content_type}")

    return {"content-type": content_type}


if __name__ == '__main__':
    uvicorn.run("main", host="127.0.0.1", port=8080)

Hope that helps

Answer 2

A better approach is to declare dependency:

from fastapi import FastAPI, HTTPException, status, Header, Depends


app = FastAPI()


def application_vnd(content_type: str = Header(...)):
    """Require request MIME-type to be application/vnd.api+json"""

    if content_type != "application/vnd.api+json":
        raise HTTPException(
            status.HTTP_415_UNSUPPORTED_MEDIA_TYPE,
            f"Unsupported media type: {content_type}."
            " It must be application/vnd.api+json",
        )


@app.post("/some-path", dependencies=[Depends(application_vnd)])
def some_path(q: str = None):
    return {"result": "All is OK!", "q": q}

So it can be reused if needed.

For successful request it'll return something like this:

{
    "result": "All is OK!",
    "q": "Some query"
}

And for unsuccessful something like this:

{
    "detail": "Unsupported media type: type/unknown-type. It must be application/vnd.api+json"
}