From 0aacbb515502a36570b0f078e3a4f548df5d3cf5 Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Thu, 10 Sep 2026 03:18:13 +0100
Subject: [PATCH 1/4] fix(querystring): preserve empty string values

---
 src/openai/_qs.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/openai/_qs.py b/src/openai/_qs.py
index 4127c19c62..d3c34ce6b0 100644
--- a/src/openai/_qs.py
+++ b/src/openai/_qs.py
@@ -112,10 +112,9 @@ def _stringify_item(
                     f"Unknown array_format value: {array_format}, choose from {', '.join(get_args(ArrayFormat))}"
                 )
 
-        serialised = self._primitive_value_to_str(value)
-        if not serialised:
+        if value is None:
             return []
-        return [(key, serialised)]
+        return [(key, self._primitive_value_to_str(value))]
 
     def _primitive_value_to_str(self, value: PrimitiveData) -> str:
         # copied from httpx

From 11607aa53993632a7a7f868ea08d6496bfde0ab3 Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Thu, 10 Sep 2026 03:18:28 +0100
Subject: [PATCH 2/4] test(querystring): cover empty string values

---
 tests/test_qs_empty_values.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 tests/test_qs_empty_values.py

diff --git a/tests/test_qs_empty_values.py b/tests/test_qs_empty_values.py
new file mode 100644
index 0000000000..658b74cc7c
--- /dev/null
+++ b/tests/test_qs_empty_values.py
@@ -0,0 +1,19 @@
+from urllib.parse import unquote
+
+from openai._qs import stringify
+
+
+def test_empty_string_scalar_is_preserved() -> None:
+    assert stringify({"filter": ""}) == "filter="
+
+
+def test_none_scalar_is_still_omitted() -> None:
+    assert stringify({"filter": None}) == ""
+
+
+def test_nested_empty_string_is_preserved() -> None:
+    assert unquote(stringify({"filter": {"name": ""}})) == "filter[name]="
+
+
+def test_empty_string_in_repeat_array_is_preserved() -> None:
+    assert stringify({"filter": ["", "active"]}) == "filter=&filter=active"

From 2eff92f005d9df6dd88ec75b864d4af9c336ae4a Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Fri, 2 Oct 2026 11:09:20 +0100
Subject: [PATCH 3/4] Omit all-None comma query arrays

---
 src/openai/_qs.py | 5 ++++-
 tests/test_qs.py  | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/openai/_qs.py b/src/openai/_qs.py
index d3c34ce6b0..8dc8b6797e 100644
--- a/src/openai/_qs.py
+++ b/src/openai/_qs.py
@@ -85,10 +85,13 @@ def _stringify_item(
         if isinstance(value, (list, tuple)):
             array_format = opts.array_format
             if array_format == "comma":
+                values = [item for item in value if item is not None]
+                if not values:
+                    return []
                 return [
                     (
                         key,
-                        ",".join(self._primitive_value_to_str(item) for item in value if item is not None),
+                        ",".join(self._primitive_value_to_str(item) for item in values),
                     ),
                 ]
             elif array_format == "repeat":
diff --git a/tests/test_qs.py b/tests/test_qs.py
index 697b8a95ec..1bcfbadedd 100644
--- a/tests/test_qs.py
+++ b/tests/test_qs.py
@@ -52,6 +52,10 @@ def test_array_comma(method: str) -> None:
     assert unquote(serialise({"in": ["foo", "bar"]})) == "in=foo,bar"
     assert unquote(serialise({"a": {"b": [True, False]}})) == "a[b]=true,false"
     assert unquote(serialise({"a": {"b": [True, False, None, True]}})) == "a[b]=true,false,true"
+    assert unquote(serialise({"filter": []})) == ""
+    assert unquote(serialise({"filter": [None]})) == ""
+    assert unquote(serialise({"filter": [""]})) == "filter="
+    assert unquote(serialise({"filter": [None, "active"]})) == "filter=active"
 
 
 def test_array_repeat() -> None:

From d42e99f921b1fb654c64a0fa8df3ff6d9f517e84 Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Sun, 4 Oct 2026 01:48:43 +0100
Subject: [PATCH 4/4] Test empty query arrays across formats

---
 tests/test_qs.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/test_qs.py b/tests/test_qs.py
index 1bcfbadedd..722c98c898 100644
--- a/tests/test_qs.py
+++ b/tests/test_qs.py
@@ -5,6 +5,7 @@
 import pytest
 
 from openai._qs import Querystring, stringify
+from openai._types import ArrayFormat
 
 
 def test_empty() -> None:
@@ -58,6 +59,13 @@ def test_array_comma(method: str) -> None:
     assert unquote(serialise({"filter": [None, "active"]})) == "filter=active"
 
 
+@pytest.mark.parametrize("array_format", ["comma", "repeat", "indices", "brackets"])
+def test_empty_array_omits_parameter(array_format: ArrayFormat) -> None:
+    # Non-empty output remains format-specific; only the empty outcome is shared.
+    assert stringify({"filter": []}, array_format=array_format) == ""
+    assert stringify({"filter": [None]}, array_format=array_format) == ""
+
+
 def test_array_repeat() -> None:
     assert unquote(stringify({"in": ["foo", "bar"]})) == "in=foo&in=bar"
     assert unquote(stringify({"a": {"b": [True, False]}})) == "a[b]=true&a[b]=false"