Optional Field args don't work as expected

[mure]

Describe the bug
When using the Field annotation on an arg to be converted into a JSON field, nullable types don't work as expected. Using Optional directly throws an error, but you can work around this by using the x | None syntax instead. However, this is causing the request body to include unintended nulls.

To Reproduce

@json
@args(Field("a"))
@patch("route")
def patch(self, a: Optional[str] = None):
   pass

Result:
TypeError: issubclass() arg 1 must be a class

@json
@args(Field("a"))
@patch("route")
def patch(self, a: str | None = None):
   pass

client.patch()

Result

{ "a": null }

It would be nice if this had the same behavior as Query params.

[mateochr]

Hi @mure found any workaround for this?

[mateochr]

I have created this class that takes the idea from the Query function annotation.

from uplink import Field


class CustomField(Field):
    def __init__(self, name=None, type=None, encode_none=None):
        super(CustomField, self).__init__(name, type)
        self._encode_none = encode_none

    def _modify_request(self, request_builder, value):
        if value is None:
            if self._encode_none is None:
                return
            value = self._encode_none

        super(CustomField, self)._modify_request(request_builder, value)

But still i don't like this approach, what if you want to pass something in the body that has None value?