litellm - 💡(How to fix) Fix [Bug] aresponses streaming on OpenAI emits Pydantic serializer warning: chat-completion Usage assigned to ResponseAPIUsage field [1 participants]

UserWarning: Pydantic serializer warnings:
  PydanticSerializationUnexpectedValue(Expected `ResponseAPIUsage` -
  serialized value may not be as expected
  [field_name='usage',
   input_value={'completion_tokens': 8, ..., 'video_tokens': None}}, input_type=dict])

---

LiteLLM:ERROR: litellm_logging.py:5553 - Error creating standard logging object - Pydantic serializer warnings: ...

---

import asyncio
import os
import warnings

import litellm

os.environ["OPENAI_API_KEY"] = "sk-..."  # replace

caught = []
def _capture(message, category, filename, lineno, file=None, line=None):
    caught.append((category.__name__, str(message), filename.split("/")[-1], lineno))
warnings.showwarning = _capture

INPUT_ITEMS = [
    {"role": "system", "content": "You answer in one short sentence."},
    {"role": "user", "content": "What is the capital of France?"},
]

async def non_stream():
    caught.clear()
    resp = await litellm.aresponses(
        model="gpt-4o-mini", input=INPUT_ITEMS, max_output_tokens=32,
    )
    print("== NON-STREAM ==")
    print(f"  usage type: {type(resp.usage).__name__}")
    for w in caught: print(f"  WARNING: {w[0]} at {w[2]}:{w[3]}")
    if not caught: print("  (no warnings)")

async def stream():
    caught.clear()
    response = await litellm.aresponses(
        model="gpt-4o-mini", input=INPUT_ITEMS, max_output_tokens=32, stream=True,
    )
    async for event in response:
        pass
    print("== STREAM ==")
    for w in caught:
        print(f"  WARNING: {w[0]} at {w[2]}:{w[3]}\n           {str(w[1])[:300]}")
    if not caught: print("  (no warnings)")

async def main():
    await non_stream()
    await stream()
    await asyncio.sleep(0.3)  # let background logging callback fire

asyncio.run(main())

---

== NON-STREAM ==
  usage type: ResponseAPIUsage
  (no warnings)
== STREAM ==
  WARNING: UserWarning at main.py:464
           Pydantic serializer warnings:
  PydanticSerializationUnexpectedValue(Expected `ResponseAPIUsage` -
  serialized value may not be as expected [field_name='usage',
  input_value={'completion_tokens': 8, ..., 'video_tokens': None}}, input_type=dict])