configurable_fields() — langchain Function Reference

Architecture documentation for the configurable_fields() function in base.py from the langchain codebase.

Function python LangChainCore Runnables calls 1

Entity Profile

LangChainCore→ Runnables→ configurable_fields() — langchain Function Reference

Dependency Diagram

graph TD
  c511db82_36ff_92db_c1e7_da221d062544["configurable_fields()"]
  163fcac0_ddd4_a382_5a54_90fc39911022["RunnableSerializable"]
  c511db82_36ff_92db_c1e7_da221d062544 -->|defined in| 163fcac0_ddd4_a382_5a54_90fc39911022
  e2bea970_c5e9_9585_6fa1_e85a5a79ce5e["with_config()"]
  c511db82_36ff_92db_c1e7_da221d062544 -->|calls| e2bea970_c5e9_9585_6fa1_e85a5a79ce5e
  style c511db82_36ff_92db_c1e7_da221d062544 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/runnables/base.py lines 2614–2670

    def configurable_fields(
        self, **kwargs: AnyConfigurableField
    ) -> RunnableSerializable[Input, Output]:
        """Configure particular `Runnable` fields at runtime.

        Args:
            **kwargs: A dictionary of `ConfigurableField` instances to configure.

        Raises:
            ValueError: If a configuration key is not found in the `Runnable`.

        Returns:
            A new `Runnable` with the fields configured.

        !!! example

            ```python
            from langchain_core.runnables import ConfigurableField
            from langchain_openai import ChatOpenAI

            model = ChatOpenAI(max_tokens=20).configurable_fields(
                max_tokens=ConfigurableField(
                    id="output_token_number",
                    name="Max tokens in the output",
                    description="The maximum number of tokens in the output",
                )
            )

            # max_tokens = 20
            print(
                "max_tokens_20: ", model.invoke("tell me something about chess").content
            )

            # max_tokens = 200
            print(
                "max_tokens_200: ",
                model.with_config(configurable={"output_token_number": 200})
                .invoke("tell me something about chess")
                .content,
            )
            ```
        """
        # Import locally to prevent circular import
        from langchain_core.runnables.configurable import (  # noqa: PLC0415
            RunnableConfigurableFields,
        )

        model_fields = type(self).model_fields
        for key in kwargs:
            if key not in model_fields:
                msg = (
                    f"Configuration key {key} not found in {self}: "
                    f"available keys are {model_fields.keys()}"
                )
                raise ValueError(msg)

        return RunnableConfigurableFields(default=self, fields=kwargs)