How to use the withFallbacks method and createReactAgent simultaneously ?

[Maimikuru]

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Example Code

import { ChatOpenAI } from "@langchain/openai";
import { webSearchTool } from "./src/tools/webSearch";

const tools = [...];

const prompt = await pull<PromptTemplate>("hwchase17/react");

export const gpt4o = new ChatOpenAI({
  model: "gpt-4o",
});

export const gpt4oMini = new ChatOpenAI({
  model: "gpt-4o-mini",
});

const model = gpt4oMini.withFallbacks([gpt4o]);

const agent = await createReactAgent({
  model,
  tools,
  prompt,
});

Description

  error: Error: llm [object Object] must define bindTools method.
      at createReactAgent (webpack-internal:///(rsc)/../../node_modules/@langchain/langgraph/dist/prebuilt/react_agent_executor.js:220:19)

This is related to the issue at #6869, however, if you use the createReactAgent while utilizing the withfallbacks method, the aforementioned error will be outputted. This is because the RunnableWithFallbacks class does not support the bindTools method. I would like to know what possible solutions there are in this case.

System Info

npm info langchain 

[email protected] | MIT | deps: 12 | versions: 315
Typescript bindings for langchain
https://github.com/langchain-ai/langchainjs/tree/main/langchain/

keywords: llm, ai, gpt3, chain, prompt, prompt engineering, chatgpt, machine learning, ml, openai, embeddings, vectorstores

dist
.tarball: https://registry.npmjs.org/langchain/-/langchain-0.3.20.tgz
.shasum: ff04db7172753923f3c8d678571244d4a6646e33
.integrity: sha512-BFCsJqKu5yJMG7AKWfTkku3rRnTGxnvi3tQXBceQt406moJ8VfZqMWrl7FC1WPkdNKinepPON2q5sb62IPoKwQ==
.unpackedSize: 2.9 MB

dependencies:
@langchain/openai: >=0.1.0 <0.6.0        openapi-types: ^12.1.3                   
@langchain/textsplitters: >=0.0.0 <0.2.0 p-retry: 4                               
js-tiktoken: ^1.0.12                     uuid: ^10.0.0                            
js-yaml: ^4.1.0                          yaml: ^2.2.1                             
jsonpointer: ^5.0.1                      zod-to-json-schema: ^3.22.3              
langsmith: >=0.2.8 <0.4.0                zod: ^3.22.4                             

maintainers:
- nfcampos <[email protected]>
- jacoblee93 <[email protected]>
- andrewnguonly <[email protected]>
- davidduong <[email protected]>
- hwchase17 <[email protected]>
- basproul <[email protected]>

dist-tags:
latest: 0.3.20                            next: 0.3.2-rc.0                          
tag-for-publishing-older-releases: 0.2.20 

published 3 days ago by jacoblee93 <[email protected]>

[dosubot[bot]]

Hola @Maimikuru! Soy un bot aquí para ayudarte a resolver errores, responder preguntas y convertirte en un contribuyente. Estoy disponible mientras esperas a un mantenedor humano. ¡Vamos a solucionar esto juntos!

A similar issue has been discussed in the LangChain JS repository, where the createReactAgent function with the withFallbacks method results in an error because the RunnableWithFallbacks class does not implement the required bindTools method ^[1].

To address this issue, you might consider the following approaches:

1. Implement bindTools Method: If possible, extend the RunnableWithFallbacks class to include a bindTools method that meets the requirements of your use case.

2. Alternative Design: Consider restructuring your code to avoid using withFallbacks in conjunction with createReactAgent, if the combination is not supported in the current version of LangChain.

3. Check for Updates: Ensure you are using the latest version of LangChain, as updates might include fixes or new features that address this issue.

These suggestions are based on the current limitations of the LangChain library version 0.3.20.

To continue talking to Dosu, mention @dosu.

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