langchain.js
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    Function registerConfigureHook

    • Register a callback configure hook to automatically add callback handlers to all runs.

      There are two ways to use this:

      1. Using a context variable:

        • Set contextVar to specify the variable name
        • Use setContextVariable() to store your handler instance
      2. Using an environment variable:

        • Set both envVar and handlerClass
        • The handler will be instantiated when the env var is set to "true".

      Parameters

      • config: ConfigureHook

        Configuration object for the hook

        • OptionalcontextVar?: string
        • OptionalenvVar?: string
        • OptionalhandlerClass?: new (...args: any[]) => BaseCallbackHandler
        • Optionalinheritable?: boolean

      Returns void

      // Method 1: Using context variable
      import {
      registerConfigureHook,
      setContextVariable
      } from "@langchain/core/context";

      const tracer = new MyCallbackHandler();
      registerConfigureHook({
      contextVar: "my_tracer",
      });
      setContextVariable("my_tracer", tracer);

      // ...run code here

      // Method 2: Using environment variable
      registerConfigureHook({
      handlerClass: MyCallbackHandler,
      envVar: "MY_TRACER_ENABLED",
      });
      process.env.MY_TRACER_ENABLED = "true";

      // ...run code here