openai[patch]: use max_completion_tokens in place of max_tokens (#26917)

`max_tokens` is deprecated:
https://platform.openai.com/docs/api-reference/chat/create#chat-create-max_tokens

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -435,7 +435,7 @@ class BaseChatOpenAI(BaseChatModel):
     """Number of chat completions to generate for each prompt."""
     top_p: Optional[float] = None
     """Total probability mass of tokens to consider at each step."""
-    max_tokens: Optional[int] = None
+    max_tokens: Optional[int] = Field(default=None)
     """Maximum number of tokens to generate."""
     tiktoken_model_name: Optional[str] = None
     """The model name to pass to tiktoken when using this class. 
@@ -699,6 +699,7 @@ class BaseChatOpenAI(BaseChatModel):
         messages = self._convert_input(input_).to_messages()
         if stop is not None:
             kwargs["stop"] = stop
+
         return {
             "messages": [_convert_message_to_dict(m) for m in messages],
             **self._default_params,
@@ -853,7 +854,9 @@ class BaseChatOpenAI(BaseChatModel):
             ls_model_type="chat",
             ls_temperature=params.get("temperature", self.temperature),
         )
-        if ls_max_tokens := params.get("max_tokens", self.max_tokens):
+        if ls_max_tokens := params.get("max_tokens", self.max_tokens) or params.get(
+            "max_completion_tokens", self.max_tokens
+        ):
             ls_params["ls_max_tokens"] = ls_max_tokens
         if ls_stop := stop or params.get("stop", None):
             ls_params["ls_stop"] = ls_stop
@@ -1501,7 +1504,7 @@ class BaseChatOpenAI(BaseChatModel):
         return filtered
 
 
-class ChatOpenAI(BaseChatOpenAI):
+class ChatOpenAI(BaseChatOpenAI):  # type: ignore[override]
     """OpenAI chat model integration.
 
     .. dropdown:: Setup
@@ -1963,6 +1966,9 @@ class ChatOpenAI(BaseChatOpenAI):
     message chunks will be generated during the stream including usage metadata.
     """
 
+    max_tokens: Optional[int] = Field(default=None, alias="max_completion_tokens")
+    """Maximum number of tokens to generate."""
+
     @property
     def lc_secrets(self) -> Dict[str, str]:
         return {"openai_api_key": "OPENAI_API_KEY"}
@@ -1992,6 +1998,29 @@ class ChatOpenAI(BaseChatOpenAI):
         """Return whether this model can be serialized by Langchain."""
         return True
 
+    @property
+    def _default_params(self) -> Dict[str, Any]:
+        """Get the default parameters for calling OpenAI API."""
+        params = super()._default_params
+        if "max_tokens" in params:
+            params["max_completion_tokens"] = params.pop("max_tokens")
+
+        return params
+
+    def _get_request_payload(
+        self,
+        input_: LanguageModelInput,
+        *,
+        stop: Optional[List[str]] = None,
+        **kwargs: Any,
+    ) -> dict:
+        payload = super()._get_request_payload(input_, stop=stop, **kwargs)
+        # max_tokens was deprecated in favor of max_completion_tokens
+        # in September 2024 release
+        if "max_tokens" in payload:
+            payload["max_completion_tokens"] = payload.pop("max_tokens")
+        return payload
+
     def _should_stream_usage(
         self, stream_usage: Optional[bool] = None, **kwargs: Any
     ) -> bool:

libs/partners/openai/tests/integration_tests/chat_models/test_base.py

@@ -44,7 +44,7 @@ def test_chat_openai() -> None:
         max_retries=3,
         http_client=None,
         n=1,
-        max_tokens=10,
+        max_completion_tokens=10,
         default_headers=None,
         default_query=None,
     )
@@ -64,7 +64,7 @@ def test_chat_openai_model() -> None:
 
 def test_chat_openai_system_message() -> None:
     """Test ChatOpenAI wrapper with system message."""
-    chat = ChatOpenAI(max_tokens=10)
+    chat = ChatOpenAI(max_completion_tokens=10)
     system_message = SystemMessage(content="You are to chat with the user.")
     human_message = HumanMessage(content="Hello")
     response = chat.invoke([system_message, human_message])
@@ -75,7 +75,7 @@ def test_chat_openai_system_message() -> None:
 @pytest.mark.scheduled
 def test_chat_openai_generate() -> None:
     """Test ChatOpenAI wrapper with generate."""
-    chat = ChatOpenAI(max_tokens=10, n=2)
+    chat = ChatOpenAI(max_completion_tokens=10, n=2)
     message = HumanMessage(content="Hello")
     response = chat.generate([[message], [message]])
     assert isinstance(response, LLMResult)
@@ -92,7 +92,7 @@ def test_chat_openai_generate() -> None:
 @pytest.mark.scheduled
 def test_chat_openai_multiple_completions() -> None:
     """Test ChatOpenAI wrapper with multiple completions."""
-    chat = ChatOpenAI(max_tokens=10, n=5)
+    chat = ChatOpenAI(max_completion_tokens=10, n=5)
     message = HumanMessage(content="Hello")
     response = chat._generate([message])
     assert isinstance(response, ChatResult)
@@ -108,7 +108,7 @@ def test_chat_openai_streaming() -> None:
     callback_handler = FakeCallbackHandler()
     callback_manager = CallbackManager([callback_handler])
     chat = ChatOpenAI(
-        max_tokens=10,
+        max_completion_tokens=10,
         streaming=True,
         temperature=0,
         callback_manager=callback_manager,
@@ -133,7 +133,9 @@ def test_chat_openai_streaming_generation_info() -> None:
 
     callback = _FakeCallback()
     callback_manager = CallbackManager([callback])
-    chat = ChatOpenAI(max_tokens=2, temperature=0, callback_manager=callback_manager)
+    chat = ChatOpenAI(
+        max_completion_tokens=2, temperature=0, callback_manager=callback_manager
+    )
     list(chat.stream("hi"))
     generation = callback.saved_things["generation"]
     # `Hello!` is two tokens, assert that that is what is returned
@@ -142,7 +144,7 @@ def test_chat_openai_streaming_generation_info() -> None:
 
 def test_chat_openai_llm_output_contains_model_name() -> None:
     """Test llm_output contains model_name."""
-    chat = ChatOpenAI(max_tokens=10)
+    chat = ChatOpenAI(max_completion_tokens=10)
     message = HumanMessage(content="Hello")
     llm_result = chat.generate([[message]])
     assert llm_result.llm_output is not None
@@ -151,7 +153,7 @@ def test_chat_openai_llm_output_contains_model_name() -> None:
 
 def test_chat_openai_streaming_llm_output_contains_model_name() -> None:
     """Test llm_output contains model_name."""
-    chat = ChatOpenAI(max_tokens=10, streaming=True)
+    chat = ChatOpenAI(max_completion_tokens=10, streaming=True)
     message = HumanMessage(content="Hello")
     llm_result = chat.generate([[message]])
     assert llm_result.llm_output is not None
@@ -161,13 +163,13 @@ def test_chat_openai_streaming_llm_output_contains_model_name() -> None:
 def test_chat_openai_invalid_streaming_params() -> None:
     """Test that streaming correctly invokes on_llm_new_token callback."""
     with pytest.raises(ValueError):
-        ChatOpenAI(max_tokens=10, streaming=True, temperature=0, n=5)
+        ChatOpenAI(max_completion_tokens=10, streaming=True, temperature=0, n=5)
 
 
 @pytest.mark.scheduled
 async def test_async_chat_openai() -> None:
     """Test async generation."""
-    chat = ChatOpenAI(max_tokens=10, n=2)
+    chat = ChatOpenAI(max_completion_tokens=10, n=2)
     message = HumanMessage(content="Hello")
     response = await chat.agenerate([[message], [message]])
     assert isinstance(response, LLMResult)
@@ -187,7 +189,7 @@ async def test_async_chat_openai_streaming() -> None:
     callback_handler = FakeCallbackHandler()
     callback_manager = CallbackManager([callback_handler])
     chat = ChatOpenAI(
-        max_tokens=10,
+        max_completion_tokens=10,
         streaming=True,
         temperature=0,
         callback_manager=callback_manager,
@@ -219,7 +221,7 @@ async def test_async_chat_openai_bind_functions() -> None:
             default=None, title="Fav Food", description="The person's favorite food"
         )
 
-    chat = ChatOpenAI(max_tokens=30, n=1, streaming=True).bind_functions(
+    chat = ChatOpenAI(max_completion_tokens=30, n=1, streaming=True).bind_functions(
         functions=[Person], function_call="Person"
     )
 
@@ -241,7 +243,7 @@ async def test_async_chat_openai_bind_functions() -> None:
 @pytest.mark.scheduled
 def test_openai_streaming() -> None:
     """Test streaming tokens from OpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     for token in llm.stream("I'm Pickle Rick"):
         assert isinstance(token.content, str)
@@ -250,7 +252,7 @@ def test_openai_streaming() -> None:
 @pytest.mark.scheduled
 async def test_openai_astream() -> None:
     """Test streaming tokens from OpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     async for token in llm.astream("I'm Pickle Rick"):
         assert isinstance(token.content, str)
@@ -259,7 +261,7 @@ async def test_openai_astream() -> None:
 @pytest.mark.scheduled
 async def test_openai_abatch() -> None:
     """Test streaming tokens from ChatOpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     result = await llm.abatch(["I'm Pickle Rick", "I'm not Pickle Rick"])
     for token in result:
@@ -269,7 +271,7 @@ async def test_openai_abatch() -> None:
 @pytest.mark.scheduled
 async def test_openai_abatch_tags() -> None:
     """Test batch tokens from ChatOpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     result = await llm.abatch(
         ["I'm Pickle Rick", "I'm not Pickle Rick"], config={"tags": ["foo"]}
@@ -281,7 +283,7 @@ async def test_openai_abatch_tags() -> None:
 @pytest.mark.scheduled
 def test_openai_batch() -> None:
     """Test batch tokens from ChatOpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     result = llm.batch(["I'm Pickle Rick", "I'm not Pickle Rick"])
     for token in result:
@@ -291,7 +293,7 @@ def test_openai_batch() -> None:
 @pytest.mark.scheduled
 async def test_openai_ainvoke() -> None:
     """Test invoke tokens from ChatOpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     result = await llm.ainvoke("I'm Pickle Rick", config={"tags": ["foo"]})
     assert isinstance(result.content, str)
@@ -300,7 +302,7 @@ async def test_openai_ainvoke() -> None:
 @pytest.mark.scheduled
 def test_openai_invoke() -> None:
     """Test invoke tokens from ChatOpenAI."""
-    llm = ChatOpenAI(max_tokens=10)
+    llm = ChatOpenAI(max_completion_tokens=10)
 
     result = llm.invoke("I'm Pickle Rick", config=dict(tags=["foo"]))
     assert isinstance(result.content, str)
@@ -385,7 +387,7 @@ async def test_astream() -> None:
             assert chunks_with_token_counts == 0
             assert full.usage_metadata is None
 
-    llm = ChatOpenAI(temperature=0, max_tokens=5)
+    llm = ChatOpenAI(temperature=0, max_completion_tokens=5)
     await _test_stream(llm.astream("Hello"), expect_usage=False)
     await _test_stream(
         llm.astream("Hello", stream_options={"include_usage": True}), expect_usage=True
@@ -393,7 +395,7 @@ async def test_astream() -> None:
     await _test_stream(llm.astream("Hello", stream_usage=True), expect_usage=True)
     llm = ChatOpenAI(
         temperature=0,
-        max_tokens=5,
+        max_completion_tokens=5,
         model_kwargs={"stream_options": {"include_usage": True}},
     )
     await _test_stream(llm.astream("Hello"), expect_usage=True)
@@ -401,7 +403,7 @@ async def test_astream() -> None:
         llm.astream("Hello", stream_options={"include_usage": False}),
         expect_usage=False,
     )
-    llm = ChatOpenAI(temperature=0, max_tokens=5, stream_usage=True)
+    llm = ChatOpenAI(temperature=0, max_completion_tokens=5, stream_usage=True)
     await _test_stream(llm.astream("Hello"), expect_usage=True)
     await _test_stream(llm.astream("Hello", stream_usage=False), expect_usage=False)
 
@@ -666,7 +668,7 @@ def test_openai_response_headers() -> None:
     """Test ChatOpenAI response headers."""
     chat_openai = ChatOpenAI(include_response_headers=True)
     query = "I'm Pickle Rick"
-    result = chat_openai.invoke(query, max_tokens=10)
+    result = chat_openai.invoke(query, max_completion_tokens=10)
     headers = result.response_metadata["headers"]
     assert headers
     assert isinstance(headers, dict)
@@ -674,7 +676,7 @@ def test_openai_response_headers() -> None:
 
     # Stream
     full: Optional[BaseMessageChunk] = None
-    for chunk in chat_openai.stream(query, max_tokens=10):
+    for chunk in chat_openai.stream(query, max_completion_tokens=10):
         full = chunk if full is None else full + chunk
     assert isinstance(full, AIMessage)
     headers = full.response_metadata["headers"]
@@ -687,7 +689,7 @@ async def test_openai_response_headers_async() -> None:
     """Test ChatOpenAI response headers."""
     chat_openai = ChatOpenAI(include_response_headers=True)
     query = "I'm Pickle Rick"
-    result = await chat_openai.ainvoke(query, max_tokens=10)
+    result = await chat_openai.ainvoke(query, max_completion_tokens=10)
     headers = result.response_metadata["headers"]
     assert headers
     assert isinstance(headers, dict)
@@ -695,7 +697,7 @@ async def test_openai_response_headers_async() -> None:
 
     # Stream
     full: Optional[BaseMessageChunk] = None
-    async for chunk in chat_openai.astream(query, max_tokens=10):
+    async for chunk in chat_openai.astream(query, max_completion_tokens=10):
         full = chunk if full is None else full + chunk
     assert isinstance(full, AIMessage)
     headers = full.response_metadata["headers"]
@@ -1085,3 +1087,13 @@ async def test_astream_response_format() -> None:
         "how are ya", response_format=Foo
     ):
         pass
+
+
+def test_o1_max_tokens() -> None:
+    response = ChatOpenAI(model="o1-mini", max_tokens=10).invoke("how are you")  # type: ignore[call-arg]
+    assert isinstance(response, AIMessage)
+
+    response = ChatOpenAI(model="gpt-4o", max_completion_tokens=10).invoke(
+        "how are you"
+    )
+    assert isinstance(response, AIMessage)

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -36,6 +36,11 @@ def test_openai_model_param() -> None:
     llm = ChatOpenAI(model_name="foo")  # type: ignore[call-arg]
     assert llm.model_name == "foo"
 
+    llm = ChatOpenAI(max_tokens=10)  # type: ignore[call-arg]
+    assert llm.max_tokens == 10
+    llm = ChatOpenAI(max_completion_tokens=10)
+    assert llm.max_tokens == 10
+
 
 def test_openai_o1_temperature() -> None:
     llm = ChatOpenAI(model="o1-preview")