fix(compat): handle None by_alias in model_dump for Pydantic v2

src/openai/_compat.py

@@ -149,7 +149,7 @@ def model_dump(
             exclude_defaults=exclude_defaults,
             # warnings are not supported in Pydantic v1
             warnings=True if PYDANTIC_V1 else warnings,
-            by_alias=by_alias,
+            by_alias=bool(by_alias) if by_alias is not None else False,
         )
     return cast(
         "dict[str, Any]",

tests/compat/test_model_dump.py

@@ -0,0 +1,23 @@
+import pydantic
+
+from openai._compat import model_dump
+
+
+class SimpleModel(pydantic.BaseModel):
+    foo: str = "bar"
+
+
+def test_model_dump_by_alias_none() -> None:
+    """Regression test for #2921: by_alias=None should not raise TypeError."""
+    result = model_dump(SimpleModel(), by_alias=None)
+    assert result == {"foo": "bar"}
+
+
+def test_model_dump_by_alias_true() -> None:
+    result = model_dump(SimpleModel(), by_alias=True)
+    assert result == {"foo": "bar"}
+
+
+def test_model_dump_by_alias_false() -> None:
+    result = model_dump(SimpleModel(), by_alias=False)
+    assert result == {"foo": "bar"}