on_custom_event() — langchain Function Reference

Source Code

libs/core/langchain_core/callbacks/manager.py lines 1565–1607

    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 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)
        if run_id is None:
            run_id = uuid7()

        handle_event(
            self.handlers,
            "on_custom_event",
            "ignore_custom_event",
            name,
            data,
            run_id=run_id,
            tags=self.tags,
            metadata=self.metadata,
        )