Issue with sending header values twice

[justmobilize]

When helping a member in the discord channel #help-with-circuitpython, I had made the mistake of thinking that this library didn't automatically deal with turning a dict into a urlencoded string. I had them convert it by hand and try and it worked.

As it turns out - it does, but also sends the header Content-Type: application/x-www-form-urlencoded, which some systems (Spotify as one) can't handle getting the header twice.

I would like to open a PR to check the header for an existing Content-Type before adding it's own (both for urlencoded and json). It would implement a method to check for an existing value since we would also want to check for casing mis-matches.

[brentru]

@justmobilize I am re-opening this issue as #149 is causing a "TypeError: wrong number of arguments" error as seen here: adafruit/Adafruit_CircuitPython_AdafruitIO#115. I am also able to locally reproduce this.

The issue appears to be with doing a GET with only headers like in adafruit_io.py's get function:

    def _get(self, path: str):
        """
        GET data from Adafruit IO

        :param str path: Formatted Adafruit IO URL from _compose_path
        """
        with self._http.get(
            path, headers=self._create_headers(self._aio_headers[1])
        ) as response:
            self._handle_error(response)
            json_data = response.json()
        return json_data

Tracing through this, your new send_header expects (self, socket, header, value). However, in this case, the header is the X-AIO-KEY and the value is of None type.

On L561, in send_header, the value is sent via _send_as_bytes but it is a NoneType where send_as_bytes expects a String:
self._send_as_bytes(socket, value)

@justmobilize Would you be able to resolve this? Do you want me to resolve this?

[justmobilize]

@brentru I'm happy to take a look at this

[justmobilize]

@brentru looking, my PR just changed from .encode to bytes

Old:

Looking at CPython requests:

If it's None it just doesn't send it, and if it's not a str it raises.

Looking into their code they:

1. Drop on None
2. Error on non str|bytes

I'll get a PR opened with tests in the next day or so.

I might recommend Adafruit_CircuitPython_AdafruitIO also add an exception here to let the user know the data is missing (otherwise I assume they would just get an auth error after the fact).

[justmobilize]

Code change here: #152. Want to make sure the method makes sense, then will add tests

[justmobilize]

@brentru just waiting on an initial code review

[justmobilize]

@brentru my code fix is merged. Can you confirm it fixes the issue and close this?

[justmobilize]

Scratch that. I see the user already tested. Closing.