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Adding memory

This shows how to add memory to an arbitrary chain. Right now, you can use the memory classes but need to hook them up manually.

Interactive tutorial
The screencast below interactively walks through an example of memory management. You can update and run the code as it's being written in the video!
import { ChatPromptTemplate, MessagesPlaceholder } from "langchain/prompts";
import { RunnableSequence } from "langchain/schema/runnable";
import { ChatAnthropic } from "langchain/chat_models/anthropic";
import { BufferMemory } from "langchain/memory";

const model = new ChatAnthropic();
const prompt = ChatPromptTemplate.fromMessages([
  ["system", "You are a helpful chatbot"],
  new MessagesPlaceholder("history"),
  ["human", "{input}"],
]);

// Default "inputKey", "outputKey", and "memoryKey values would work here
// but we specify them for clarity.
const memory = new BufferMemory({
  returnMessages: true,
  inputKey: "input",
  outputKey: "output",
  memoryKey: "history",
});

console.log(await memory.loadMemoryVariables({}));

/*
  { history: [] }
*/

const chain = RunnableSequence.from([
  {
    input: (initialInput) => initialInput.input,
    memory: () => memory.loadMemoryVariables({}),
  },
  {
    input: (previousOutput) => previousOutput.input,
    history: (previousOutput) => previousOutput.memory.history,
  },
  prompt,
  model,
]);

const inputs = {
  input: "Hey, I'm Bob!",
};

const response = await chain.invoke(inputs);

console.log(response);

/*
  AIMessage {
    content: " Hi Bob, nice to meet you! I'm Claude, an AI assistant created by Anthropic to be helpful, harmless, and honest.",
    additional_kwargs: {}
  }
*/

await memory.saveContext(inputs, {
  output: response.content,
});

console.log(await memory.loadMemoryVariables({}));

/*
  {
    history: [
      HumanMessage {
        content: "Hey, I'm Bob!",
        additional_kwargs: {}
      },
      AIMessage {
        content: " Hi Bob, nice to meet you! I'm Claude, an AI assistant created by Anthropic to be helpful, harmless, and honest.",
        additional_kwargs: {}
      }
    ]
  }
*/

const inputs2 = {
  input: "What's my name?",
};

const response2 = await chain.invoke(inputs2);

console.log(response2);

/*
  AIMessage {
    content: ' You told me your name is Bob.',
    additional_kwargs: {}
  }
*/

API Reference: