Mongoose

安装

npm install mongoose

连接数据库

const mongoose = require('mongoose')

mongoose.connect('mongodb://localhost:27017/test') // 连接数据库
// 数据库连接失败和成功函数
const db = mongoose.connection

db.on('error', error => console.error(error))

db.on('open', () => console.log('数据库连接成功'))

插入数据

db.on('open', () => {
  // 定义数据模型
  const KittenSchema = new mongoose.Schema({
    name: String
  })
  // 将schema转化为model
  const Kitten = mongoose.model('Kitten', KittenSchema)

  const kitten = new Kitten({
    name:'喵喵喵'
  })
  kitten.save().then(() => {
    console.log('数据存储成功')
  })
})

把数据库连接代码改造成Promise

const mongoose = require('mongoose')
const dbs = 'mongodb://localhost:27017/test'
exports.connect = () => {

  let maxConnectTimes = 0

  return new Promise((resolve, reject) => {
    mongoose.connect(dbs) // 连接数据库
    // 数据库连接失败和成功函数
    const db = mongoose.connection
  
    db.on('disconnected', () => {
      maxConnectTimes++
      if (maxConnectTimes < 5) {
        mongoose.connect(dbs) // 重新连接数据库
      } else {
        reject('数据库挂了')
      }
    })

    db.on('error', err => {
      if (maxConnectTimes >= 5) {
        reject(err)
      }
    })
    
    db.on('open', () => {
      resolve()
     console.log('数据库连接成功')
    })
  })
}