BaseChatOpenAI Class — langchain Architecture

Source Code

libs/partners/openai/langchain_openai/chat_models/base.py lines 513–2259

class BaseChatOpenAI(BaseChatModel):
    """Base wrapper around OpenAI large language models for chat."""

    client: Any = Field(default=None, exclude=True)

    async_client: Any = Field(default=None, exclude=True)

    root_client: Any = Field(default=None, exclude=True)

    root_async_client: Any = Field(default=None, exclude=True)

    model_name: str = Field(default="gpt-3.5-turbo", alias="model")
    """Model name to use."""

    temperature: float | None = None
    """What sampling temperature to use."""

    model_kwargs: dict[str, Any] = Field(default_factory=dict)
    """Holds any model parameters valid for `create` call not explicitly specified."""

    openai_api_key: (
        SecretStr | None | Callable[[], str] | Callable[[], Awaitable[str]]
    ) = Field(
        alias="api_key", default_factory=secret_from_env("OPENAI_API_KEY", default=None)
    )
    """API key to use.

    Can be inferred from the `OPENAI_API_KEY` environment variable, or specified as a
    string, or sync or async callable that returns a string.

    ??? example "Specify with environment variable"

        ```bash
        export OPENAI_API_KEY=...
        ```
        ```python
        from langchain_openai import ChatOpenAI

        model = ChatOpenAI(model="gpt-5-nano")
        ```

    ??? example "Specify with a string"

        ```python
        from langchain_openai import ChatOpenAI

        model = ChatOpenAI(model="gpt-5-nano", api_key="...")
        ```

    ??? example "Specify with a sync callable"
        ```python
        from langchain_openai import ChatOpenAI

        def get_api_key() -> str:
            # Custom logic to retrieve API key
            return "..."

        model = ChatOpenAI(model="gpt-5-nano", api_key=get_api_key)
        ```

    ??? example "Specify with an async callable"
        ```python
        from langchain_openai import ChatOpenAI

        async def get_api_key() -> str:
            # Custom async logic to retrieve API key
            return "..."

        model = ChatOpenAI(model="gpt-5-nano", api_key=get_api_key)
        ```
    """

    openai_api_base: str | None = Field(default=None, alias="base_url")
    """Base URL path for API requests, leave blank if not using a proxy or service emulator."""  # noqa: E501

    openai_organization: str | None = Field(default=None, alias="organization")
    """Automatically inferred from env var `OPENAI_ORG_ID` if not provided."""

    # to support explicit proxy for OpenAI
    openai_proxy: str | None = Field(
        default_factory=from_env("OPENAI_PROXY", default=None)