expressServer/config/mongodbConfig.js

const mongoose = require('mongoose')
require('dotenv').config() // 加载 .env 文件

// 使用环境变量存储敏感信息
const account = process.env.MONGO_ACCOUNT
const password = process.env.MONGO_PASSWORD
const host = process.env.MONGO_HOST || '122.152.201.90'
const port = process.env.MONGO_PORT || '27017'

let isConnected = false

exports.connectMongoDB = async function () {
  if (process.env.NODE_ENV === 'development') {
    console.log(account, password, host, port)
  }

  // 如果已经连接，不再重复连接
  if (isConnected) {
    console.log('MongoDB 已经连接')
    return
  }

  try {
    const mongoDBUrl = `mongodb://${account}:${password}@${host}:${port}`

    mongoose.connect(mongoDBUrl)

    mongoose.connection.on('open', () => {
      console.log('MongoDB 连接成功')
      isConnected = true
    })

    mongoose.connection.on('error', (err) => {
      console.error('MongoDB 连接错误:', err.message)
      isConnected = false
    })

    mongoose.connection.on('close', () => {
      console.log('MongoDB 连接关闭')
      isConnected = false
    })
  } catch (err) {
    console.error('MongoDB 连接初始化失败:', err.message)
    throw err
  }
}