KV should raise an error if the key contains unacceptable characters

[kevinhikaruevans]

Proposed change

If the key contains unacceptable characters (e.g. whitespace), an error should be raised. Maybe BadSubjectError can be reused or a new error can be created (e.g. BadKeyError).

It currently gives an UnexpectedEOF error and causes a TimeoutError. This is fairly confusing because it doesn't necessarily imply the key is bad and could be remedied by a quick check on the key.

Use case

I had somebody else feeding me some data, which was being fed into nats kv. I noticed that occasionally, an entry would cause an eof error and a timeout error and it wasn't very clear why. I finally realized that the user was putting spaces in the keys, which was causing problems in the underlying publish() call.

Contribution

Sure. I would assume it would be putting in a little check in put()

[caspervonb]

I'd consider this a defect, we should match the validation that Go does in this case (https://github.com/nats-io/nats.go/blob/main/kv.go#L558)

[skewty]

Is this not the Primitive Obsession code smell?

https://refactoring.guru/smells/primitive-obsession

from typing import Final, Self
import re

class Key(str):
    PATTERN: Final = re.compile(r"^[A-Za-z_-]+[A-Za-z0-9_-]*$")  # whatever you want / need

    def __new__(cls, *args, **kwargs) -> Self:
        value = super().__new__(cls, *args, **kwargs)
        # really any checks you require here but likely regex will suffice
        if cls.PATTERN.match(value) is None:
            raise ValueError(f'Key {value} contains invalid characters')
        return value

[skewty]

IMO these Value classes should be used elsewhere in the code-base as well. Example bucket name.