Handle None created timestamp coming from OpenRouter API (#2247)

Co-authored-by: Douwe Maan <douwe@pydantic.dev>

Author: R0boji

pydantic_ai_slim/pydantic_ai/models/openai.py

@@ -17,7 +17,7 @@
 
 from .. import ModelHTTPError, UnexpectedModelBehavior, _utils, usage
 from .._output import DEFAULT_OUTPUT_TOOL_NAME, OutputObjectDefinition
-from .._utils import guard_tool_call_id as _guard_tool_call_id, number_to_datetime
+from .._utils import guard_tool_call_id as _guard_tool_call_id, now_utc as _now_utc, number_to_datetime
 from ..messages import (
     AudioUrl,
     BinaryContent,
@@ -357,11 +357,17 @@ def _process_response(self, response: chat.ChatCompletion | str) -> ModelRespons
         if not isinstance(response, chat.ChatCompletion):
             raise UnexpectedModelBehavior('Invalid response from OpenAI chat completions endpoint, expected JSON data')
 
+        if response.created:
+            timestamp = number_to_datetime(response.created)
+        else:
+            timestamp = _now_utc()
+            response.created = int(timestamp.timestamp())
+
         try:
             response = chat.ChatCompletion.model_validate(response.model_dump())
         except ValidationError as e:
             raise UnexpectedModelBehavior(f'Invalid response from OpenAI chat completions endpoint: {e}') from e
-        timestamp = number_to_datetime(response.created)
+
         choice = response.choices[0]
         items: list[ModelResponsePart] = []
         # The `reasoning_content` is only present in DeepSeek models.

tests/models/test_openai.py

@@ -2599,7 +2599,7 @@ async def test_invalid_response(allow_model_requests: None):
     with pytest.raises(UnexpectedModelBehavior) as exc_info:
         await agent.run('What is the capital of France?')
     assert exc_info.value.message.startswith(
-        'Invalid response from OpenAI chat completions endpoint: 5 validation errors for ChatCompletion'
+        'Invalid response from OpenAI chat completions endpoint: 4 validation errors for ChatCompletion'
     )
 
 
@@ -2615,3 +2615,19 @@ async def test_text_response(allow_model_requests: None):
     assert exc_info.value.message == snapshot(
         'Invalid response from OpenAI chat completions endpoint, expected JSON data'
     )
+
+
+async def test_process_response_no_created_timestamp(allow_model_requests: None):
+    c = completion_message(
+        ChatCompletionMessage(content='world', role='assistant'),
+    )
+    c.created = None  # type: ignore
+
+    mock_client = MockOpenAI.create_mock(c)
+    m = OpenAIModel('gpt-4o', provider=OpenAIProvider(openai_client=mock_client))
+    agent = Agent(m)
+    result = await agent.run('Hello')
+    messages = result.all_messages()
+    response_message = messages[1]
+    assert isinstance(response_message, ModelResponse)
+    assert response_message.timestamp == IsNow(tz=timezone.utc)