Postgres 聊天记忆

为了在聊天会话之间实现更长期的持久性，您可以将默认的内存中 chatHistory 替换为 Postgres 数据库。

设置

首先安装 node-postgres 包

提示

请参阅 此部分了解安装集成包的一般说明。

npm

npm install @langchain/openai @langchain/community @langchain/core pg

Yarn

yarn add @langchain/openai @langchain/community @langchain/core pg

pnpm

pnpm add @langchain/openai @langchain/community @langchain/core pg

用法

每个聊天历史记录会话都存储在 Postgres 数据库中，并需要一个会话 ID。

与 postgres 的连接通过池处理。您可以通过 pool 参数传递池实例，也可以通过 poolConfig 参数传递池配置。有关详细信息，请参阅 pg-node 池文档。提供的池优先，因此，如果同时传递了池实例和池配置，则只使用池。

import pg from "pg";

import { PostgresChatMessageHistory } from "@langchain/community/stores/message/postgres";
import { ChatOpenAI } from "@langchain/openai";
import { RunnableWithMessageHistory } from "@langchain/core/runnables";
import {
  ChatPromptTemplate,
  MessagesPlaceholder,
} from "@langchain/core/prompts";
import { StringOutputParser } from "@langchain/core/output_parsers";

const poolConfig = {
  host: "127.0.0.1",
  port: 5432,
  user: "myuser",
  password: "ChangeMe",
  database: "api",
};

const pool = new pg.Pool(poolConfig);

const model = new ChatOpenAI();

const prompt = ChatPromptTemplate.fromMessages([
  [
    "system",
    "You are a helpful assistant. Answer all questions to the best of your ability.",
  ],
  new MessagesPlaceholder("chat_history"),
  ["human", "{input}"],
]);

const chain = prompt.pipe(model).pipe(new StringOutputParser());

const chainWithHistory = new RunnableWithMessageHistory({
  runnable: chain,
  inputMessagesKey: "input",
  historyMessagesKey: "chat_history",
  getMessageHistory: async (sessionId) => {
    const chatHistory = new PostgresChatMessageHistory({
      sessionId,
      pool,
      // Can also pass `poolConfig` to initialize the pool internally,
      // but easier to call `.end()` at the end later.
    });
    return chatHistory;
  },
});

const res1 = await chainWithHistory.invoke(
  {
    input: "Hi! I'm MJDeligan.",
  },
  { configurable: { sessionId: "langchain-test-session" } }
);
console.log(res1);
/*
  "Hello MJDeligan! It's nice to meet you. My name is AI. How may I assist you today?"
*/

const res2 = await chainWithHistory.invoke(
  { input: "What did I just say my name was?" },
  { configurable: { sessionId: "langchain-test-session" } }
);
console.log(res2);

/*
  "You said your name was MJDeligan."
*/

// If you provided a pool config you should close the created pool when you are done
await pool.end();

API 参考

• PostgresChatMessageHistory 来自 @langchain/community/stores/message/postgres
• ChatOpenAI 来自 @langchain/openai
• RunnableWithMessageHistory 来自 @langchain/core/runnables
• ChatPromptTemplate 来自 @langchain/core/prompts
• MessagesPlaceholder 来自 @langchain/core/prompts
• StringOutputParser 来自 @langchain/core/output_parsers