Change QueryParams(key=None) to not emit a parameter

This one I know is requests behaviour:

Take a dict:

>>> from httpx import QueryParams
>>> params = {"thing_one": 1, "thing_two": [1,2,3], "thing_three": None}
>>> QueryParams(params)
QueryParams('thing_one=1&thing_two=%5B1%2C+2%2C+3%5D&thing_three=None')

Expected:

QueryParams('thing_one=1&thing_two=%5B1%2C+2%2C+3%5D')

Adding if v is not None here will do it.

[sethmlarson]

Since I’m no longer on mobile and can type symbols easily I’m proposing:

• {"q": "1"} -> ?q=1
• {"q": ""} -> ?q=
• {"q": None} -> ?q

There are also instances where the order matters for the parameters, so maybe we need to allow typing.Iterable[typing.Tuple[typing.AnyStr, typing.AnyStr]] in addition to dict?

[StephenBrown2]

I’m using Pydantic to roundtrip my params and standardize on values with custom validators/parsers: https://pydantic-docs.helpmanual.io/#json-serialisation so I’m sure some inspiration could be taken from that.

I would not be opposed to the latter, especially since query params can imitate form data, they should also allow lists, and explode them since QueryParams is already a multi-dict. This however could be left up to the user.