db.ts

import { MongoClient, ServerApiVersion } from "mongodb";

const uri = "mongodb://salt:yelsjdhl@maimap-mysql.mfnest.tech:27017/maimap";
// 可使用公用的MongoDB Atlas数据库进行开发
// const uri = "mongodb+srv://salt:yelsjdhl@maimap.uqvlj.mongodb.net/"
const options = {
  serverApi: {
    version: ServerApiVersion.v1,
    strict: true,
    deprecationErrors: true,
  },
};

let client: MongoClient;

if (process.env.NODE_ENV === "development") {
  // In development mode, use a global variable so that the value
  // is preserved across module reloads caused by HMR (Hot Module Replacement).
  let globalWithMongo = global as typeof globalThis & {
    _mongoClient?: MongoClient;
  };

  if (!globalWithMongo._mongoClient) {
    globalWithMongo._mongoClient = new MongoClient(uri, options);
  }
  client = globalWithMongo._mongoClient;
} else {
  // In production mode, it's best to not use a global variable.
  client = new MongoClient(uri, options);
}

// Export a module-scoped MongoClient. By doing this in a
// separate module, the client can be shared across functions.
export default client;