on_custom_event() — langchain Function Reference

Architecture documentation for the on_custom_event() function in manager.py from the langchain codebase.

Function python Observability CallbackManager calls 2 called by 1

Entity Profile

Observability→ CallbackManager→ on_custom_event() — langchain Function Reference

Dependency Diagram

graph TD
  1425c66d_ea29_8195_679d_7f9b37f666b9["on_custom_event()"]
  90ea8982_7d84_5e8f_4b5a_533f89fc7211["AsyncCallbackManager"]
  1425c66d_ea29_8195_679d_7f9b37f666b9 -->|defined in| 90ea8982_7d84_5e8f_4b5a_533f89fc7211
  05ff15a0_d0e7_0677_7cd8_d872844c3ecf["on_custom_event()"]
  05ff15a0_d0e7_0677_7cd8_d872844c3ecf -->|calls| 1425c66d_ea29_8195_679d_7f9b37f666b9
  05ff15a0_d0e7_0677_7cd8_d872844c3ecf["on_custom_event()"]
  1425c66d_ea29_8195_679d_7f9b37f666b9 -->|calls| 05ff15a0_d0e7_0677_7cd8_d872844c3ecf
  3a243d21_72d1_dca9_f7be_acbb482b9f86["ahandle_event()"]
  1425c66d_ea29_8195_679d_7f9b37f666b9 -->|calls| 3a243d21_72d1_dca9_f7be_acbb482b9f86
  style 1425c66d_ea29_8195_679d_7f9b37f666b9 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/callbacks/manager.py lines 2037–2079

    async def on_custom_event(
        self,
        name: str,
        data: Any,
        run_id: UUID | None = None,
        **kwargs: Any,
    ) -> None:
        """Dispatch an adhoc event to the handlers (async version).

        This event should NOT be used in any internal LangChain code. The event is meant
        specifically for users of the library to dispatch custom events that are
        tailored to their application.

        Args:
            name: The name of the adhoc event.
            data: The data for the adhoc event.
            run_id: The ID of the run.

        Raises:
            ValueError: If additional keyword arguments are passed.
        """
        if not self.handlers:
            return
        if run_id is None:
            run_id = uuid7()

        if kwargs:
            msg = (
                "The dispatcher API does not accept additional keyword arguments."
                "Please do not pass any additional keyword arguments, instead "
                "include them in the data field."
            )
            raise ValueError(msg)
        await ahandle_event(
            self.handlers,
            "on_custom_event",
            "ignore_custom_event",
            name,
            data,
            run_id=run_id,
            tags=self.tags,
            metadata=self.metadata,
        )