AttributeError exception when raising HTTPException using headers parameter

[DorAbu]

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Example Code

from fastapi import FastAPI, HTTPException

app = FastAPI()


@app.get("/")
async def root():
    raise HTTPException(
        status_code=503,
        detail=f"The server is not ready to handle the request, due to ...",
        headers={"Retry-After": 20}
    )

Description

In HTTPException object signature (attached below 1.), headers type hint is Optional[Dict[str, Any]].
But for example, when Dict[str, int] is given as in the "example code" section, the implementation in Starlette will raise an exception - AttributeError: 'int' object has no attribute 'encode' (attached below 2.).

Seems that Starlette implementation expects Optional[Dict[str, str]] type hint, FastAPI may resolve it by converting the values of the headers to strings.

1. 
2. 

Operating System

Windows

Operating System Details

No response

FastAPI Version

0.70.1

Python Version

3.8.9 (tags/v3.8.9:a743f81, Apr 6 2021, 14:02:34) [MSC v.1928 64 bit (AMD64)]

Additional Context

starlette==0.16.0

[harunyasar]

I am a bit confused. This function signature below clearly shows that it is supposed to be a str.

https://github.com/encode/starlette/blob/34d9f0f10f2e4706551acf340eb1eaf4d8c87b49/starlette/responses.py#L59

[DorAbu]

Yes but I referred to the signature of the HTTPException object, please check the attached print screen

[tiangolo]

Indeed! This is wrong. The type annotation should define that it expects a str as value. I just fixed it in #9648

The fix will be available in the next version, released in a few hours (the current version is 0.96.0).