Function●Since v1.0

dispatchCustomEvent

Dispatch a custom event.

Note: this method is only supported in non-web environments due to usage of async_hooks to infer config.

If you are using this method in the browser, please import and use from "@langchain/core/callbacks/dispatch/web".

dispatchCustomEvent(
  eventName: string,
  payload: any,
  config: RunnableConfig<Record<string, any>>
): Promise<void>

Parameters

Name	Type	Description
`eventName`*	`string`
`payload`*	`any`	The data for the custom event. Ideally should be JSON serializable to avoid serialization issues downstream, but not enforced.
`config`	`RunnableConfig<Record<string, any>>`	Optional config object.

Example

import { dispatchCustomEvent } from "@langchain/core/callbacks/dispatch";

const foo = RunnableLambda.from(async (input: string) => {
  await dispatchCustomEvent("my_custom_event", { arbitraryField: "someval" });
  return input;
});

const callbacks = [{
  handleCustomEvent: (eventName: string, payload: any) => {
    // Logs "my_custom_event" and { arbitraryField: "someval" }
    console.log(eventName, payload);
  }
}];

await foo.invoke("hi", { callbacks })

View source on GitHub

dispatchCustomEvent

Parameters

Example

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dispatchCustomEvent

Parameters

Example