Error executing `lib/langfontfinder/api.py`

[imnasnainaec]

Here's the error

Traceback (most recent call last):
  File "C:\Users\danie\imnasnainaec\langfontfinder\lib\langfontfinder\api.py", line 33, in <module>
    async def lang(response: Response, ltag: str = Path("", description="Language tag")):
                                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\danie\imnasnainaec\langfontfinder\venv\Lib\site-packages\fastapi\param_functions.py", line 54, in Path
    return params.Path(
           ^^^^^^^^^^^^
  File "C:\Users\danie\imnasnainaec\langfontfinder\venv\Lib\site-packages\fastapi\params.py", line 178, in __init__
    assert default is ..., "Path parameters cannot have a default value"
           ^^^^^^^^^^^^^^
AssertionError: Path parameters cannot have a default value

I'm on Windows 11 using Python 3.11 with the following libraries loaded:

annotated-types==0.5.0
anyio==3.7.1
certifi==2023.7.22
click==8.1.6
colorama==0.4.6
fastapi==0.101.1
h11==0.14.0
httpcore==0.17.3
httpx==0.24.1
idna==3.4
langtag @ git+https://github.com/silnrsi/langtags@master
pydantic==2.1.1
pydantic-core==2.4.0
sniffio==1.3.0
starlette==0.27.0
typing-extensions==4.7.1
uvicorn==0.23.2

[imnasnainaec]

In https://github.com/silnrsi/langfontfinder/blob/main/lib/langfontfinder/api.py#L33-L41, changing

• Path("", description="Language tag")) -> Path(description="Language tag"))
• Path("", description="Font family id")) -> Path(description="Font family id"))

... eliminated the error, so when I run api.py I get:

INFO:     Started server process [6636]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

But then http://127.0.0.1:8000 only shows {"detail":"Not Found"} so I don't know if that correctly fixes the issue.

[imnasnainaec]

Potential pr with that change: https://github.com/silnrsi/langfontfinder/compare/main...imnasnainaec:langfontfinder:lib-langfontfinder-apy-py-path-default

[imnasnainaec]

@DavidLRowe When running lib/langfontfinder/api.py, is the expected default to see {"detail":"Not Found"} at http://127.0.0.1:8000?

[DavidLRowe]

@mhosken Can you comment on this issue when you have the time?

[mhosken]

My guess this comes from building on sand. Sigh. I so liked the conservative nature of python in the past. Ah well. I'm quite happy seeing this change so long as it doesn't break the server.

[mhosken]

Pulling @tim-eves to check this isn't going to break production

[DavidLRowe]

@imnasnainaec Thanks for reporting this. It seems to be due to you using a later version of fastapi than we currently have. @tim-eves plans to implement your suggestion for changes, then include a version in the requirements.txt in order to catch any similar changes in future.

The {"detail":"Not Found"} return is expected. It is essentially a text rendering of the 404 "Not Found" response that happens when there's a missing parameter.

Thanks again for reporting this.

[DavidLRowe]

I'll wait to close this until the fix is actually in place.

[tim-eves]

Fixed in GH-15, in turns out this was always a problem because Path() parameters are always required so the default value is nonsensical for a Path. The newer version just got stricter about not allowing it.