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How to use multiple memory classes in the same chain

It is also possible to use multiple memory classes in the same chain. To combine multiple memory classes, we can initialize the CombinedMemory class, and then use that.

import { ChatOpenAI } from "langchain/chat_models/openai";
import {
  BufferMemory,
  CombinedMemory,
  ConversationSummaryMemory,
} from "langchain/memory";
import { ConversationChain } from "langchain/chains";
import { PromptTemplate } from "langchain/prompts";

// buffer memory
const bufferMemory = new BufferMemory({
  memoryKey: "chat_history_lines",
  inputKey: "input",
});

// summary memory
const summaryMemory = new ConversationSummaryMemory({
  llm: new ChatOpenAI({ modelName: "gpt-3.5-turbo", temperature: 0 }),
  inputKey: "input",
  memoryKey: "conversation_summary",
});

//
const memory = new CombinedMemory({
  memories: [bufferMemory, summaryMemory],
});

const _DEFAULT_TEMPLATE = `The following is a friendly conversation between a human and an AI. The AI is talkative and provides lots of specific details from its context. If the AI does not know the answer to a question, it truthfully says it does not know.

Summary of conversation:
{conversation_summary}
Current conversation:
{chat_history_lines}
Human: {input}
AI:`;

const PROMPT = new PromptTemplate({
  inputVariables: ["input", "conversation_summary", "chat_history_lines"],
  template: _DEFAULT_TEMPLATE,
});
const model = new ChatOpenAI({ temperature: 0.9, verbose: true });
const chain = new ConversationChain({ llm: model, memory, prompt: PROMPT });

const res1 = await chain.call({ input: "Hi! I'm Jim." });
console.log({ res1 });

/*
  {
    res1: {
      response: "Hello Jim! It's nice to meet you. How can I assist you today?"
    }
  }
*/

const res2 = await chain.call({ input: "Can you tell me a joke?" });
console.log({ res2 });

/*
  {
    res2: {
      response: 'Why did the scarecrow win an award? Because he was outstanding in his field!'
    }
  }
*/

const res3 = await chain.call({
  input: "What's my name and what joke did you just tell?",
});
console.log({ res3 });

/*
  {
    res3: {
      response: 'Your name is Jim. The joke I just told was about a scarecrow winning an award because he was outstanding in his field.'
    }
  }
*/

API Reference: