Implementation:Langchain ai Langchain ChatOpenAI Constructor For Streaming

Knowledge Sources	LangChain
Domains	NLP, Streaming
Last Updated	2026-02-11 00:00 GMT

Overview

Concrete tool for initializing OpenAI chat models with streaming configuration provided by the LangChain OpenAI integration.

Description

The same ChatOpenAI class is used for streaming, with specific attention to streaming-related fields: streaming (default streaming behavior), disable_streaming (conditional override), and stream_usage (token usage in chunks). When streaming=True, even invoke() calls use the streaming path internally.

Usage

Initialize ChatOpenAI with streaming=True for applications that primarily use streaming, or leave it as False and use stream() explicitly.

Code Reference

Source Location

• Repository: langchain
• File: libs/partners/openai/langchain_openai/chat_models/base.py
• Lines: L513-2260 (BaseChatOpenAI), L2262-3493 (ChatOpenAI)

Signature

class BaseChatOpenAI(BaseChatModel):
    # Streaming-relevant fields:
    streaming: bool = False
    disable_streaming: bool | Literal["tool_calling"] = False
    stream_usage: bool = True

Import

from langchain_openai import ChatOpenAI

I/O Contract

Inputs

Name	Type	Required	Description
streaming	bool	No (default: False)	Enable streaming by default in invoke()
disable_streaming	bool or Literal["tool_calling"]	No (default: False)	Disable streaming globally or for tool calls
stream_usage	bool	No (default: True)	Include token usage metadata in stream chunks

Outputs

Name	Type	Description
instance	ChatOpenAI	Model configured for streaming

Usage Examples

Streaming Configuration

from langchain_openai import ChatOpenAI

# Streaming by default (invoke() will stream internally)
llm = ChatOpenAI(model="gpt-4o-mini", streaming=True)

# Explicit streaming (invoke() does not stream, stream() does)
llm = ChatOpenAI(model="gpt-4o-mini")
for chunk in llm.stream("Tell me a story"):
    print(chunk.content, end="", flush=True)

Related Pages

Implements Principle

• Principle:Langchain_ai_Langchain_Chat_Model_Initialization_For_Streaming
• Environment:Langchain_ai_Langchain_OpenAI_API_Credentials