手把手教你基于koa2，mongoose实现增删改查

• 初始化项目

npm init -y

• 先安装一波乱七八糟的依赖插件（需要具备一定的koa2知识，至于mongoDB自行百度安装教程）,模板引擎我使用的是art-template（据说是性能最好的，而且是因为JQ时代的产物，念旧）

npm i koa koa-router koa-bodyparser koa-static koa-views art-template koa-art-template mongoose  -S

• 安装nodemon实时监听修改

npm i nodemon -D

• 新建app.js入口文件，撸一把基础代码

const Koa = require('koa')
const app = new Koa()
const views = require('koa-views')

const bodyParser = require('koa-bodyparser')
// const Router = require('koa-router')
const path = require('path')
// const router = new Router()

const {connect} = require('./dbs/init.js')  //导入mongodb数据库
const {createUser} = require('./controller/users.js')

// 模板引擎
const render = require('koa-art-template');
render(app, {
  root: path.join(__dirname, 'views'),
  extname: '.html',
  debug: process.env.NODE_ENV !== 'production'
});

//自执行函数，链接数据库
;(async ()=>{
  await connect()
})()

const userRouter = require('./controller/users.js')
app.use(userRouter.routes(),userRouter.allowedMethods())
// app.use(router.routes(),router.allowedMethods())

app
  .use(bodyParser({enableTypes:['json', 'form', 'text']}))
  .use(require('koa-static')(__dirname + '/public'))
  .use(views(__dirname + '/views', {
    extension: 'html'
  }))

app.listen(4000,()=>{
  console.log('listen at port localhost:4000 ');
})

• 新建dbs文件夹，在下面统一管理数据库相关，新建init.js数据库初始化

const mongoose = require('mongoose')
const db = 'mongodb://localhost/mongo_test'; //link
// const glob = require('glob')
// const {resolve} = require('path')

// exports.initSchemas = ()=>{
//   // glob.sync(resolve(__dirname,'./schema','**/*.js')).forEach(require)
// }

// 连接数据库，URL以mongodb:// + [用户名:密码@] +数据库地址[:端口] + 数据库名。（默认端口27017）
// 连接mongodb数据库的链接解析器会在未来移除，要使用新的解析器，通过配置{ useNewUrlParser:true }来连接 ；其他警告参考：https://mongoosejs.com/docs/deprecations.html

/**
 * mongoose从@5.2.8后会弃用一些指令，为防止程序如下警告：
 * (node:24864) DeprecationWarning: collection.ensureIndex is deprecated. Use createIndexes instead.
 * (node:24841) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
 * 可以如下设置
 */
mongoose.set('useNewUrlParser', true)
mongoose.set('useFindAndModify', false)
mongoose.set('useCreateIndex', true)
let dbc = mongoose.connection
exports.connect = ()=> {
  // 链接数据库
  mongoose.connect(db)
  let  maxConnectTimes = 0

  return new Promise((resolve,reject)=>{

    // 增加数据库监听事件:断开链接
    dbc.on('disconnected',()=>{
      console.log('***********数据库断开***********')
      if(maxConnectTimes<=3){
        maxConnectTimes++
        mongoose.connect(db)
      }
      else {
        reject()
        throw new Error('数据库出现问题，请人为修理.....')
      }
    })

    dbc.on('error',err=>{
      console.log('***********数据库出错***********')
      if(maxConnectTimes<=3){
        maxConnectTimes++
        mongoose.connect(db)
      }
      else {
        reject()
        throw new Error('数据库出现问题，请人为修理.....')
      }

    })

    dbc.once('open',()=>{
      console.log('MongoDB Connected successfully!')
      resolve()
    })
  })

}

• 在dbs文件夹下新建schema文件夹用于创建各种schema表，新建Users.js

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

let ObjectId = Schema.Types.ObjectId;

const userSchema = new Schema({
  UserId : {type:ObjectId},
  userName:{unique:true,type:String},//unique表示索引唯一
  password:String,
  gender:Number,
  userStatus:Number,
  createAt:{type:Date,default:Date.now()},
  lastLoginAt:{type:Date,default:Date.now()}
},{collection:'users'})

const model = {
  Users:mongoose.model('Users',userSchema)
}

// 发布模型
module.exports = model

• 新建controller文件夹，主要是用来处理一些业务逻辑，新建users.js文件

let {
  addUser,
  updateUser,
  delUser,
  findAllUsers,
  findOne
} = require('./tools.js');

const common = require("../libs/common");
const Users = require('../dbs/schema/Users.js').Users
const Router = require('koa-router') ;

let router = new Router()
router.prefix('/user')
// 查找列表
router.get('/list',async (ctx)=>{
  let code = 0 // 状态码
  let msg = '' // 返回内容
  let {keyword} = ctx.query ;
  let params = {
    keyword
  }
  let ret = await findAllUsers(params)
  ctx.body = {
    code,
    list:ret,
    msg:'操作成功'
  }
})
// 查找信息
router.get('/detail',async (ctx)=>{
  let code = 0 // 状态码
  let msg = '' // 返回内容
  let {id} = ctx.query ;
  let params = {
    id
  }
  let ret = await findOne(params)
  ctx.body = {
    code,
    list:ret,
    msg:'操作成功'
  }
})
router.post('/addUser',async (ctx)=>{
  let code = 0 // 状态码
  let msg = '' // 返回内容

  let {userName,password,gender,type,id} = ctx.request.body ;

  if(type=='edit'){
    if(id){
      let ret = await updateUser(ctx.request.body)
      if(ret.ok==1){
        code = 0
        msg = '修改成功'
      }
      else {
        code = -1
        msg = '修改失败,'
      }
    }
    else{
      code = -1
      msg = '参数错误,'
    }
  }
  // 删除
  else {
    // let id = common.uuid();
    let user = new Users({
      userName,
      password,
      gender,
      userStatus:1
    })
    try {
      let ret = await addUser(user)
      console.log(ret);

      code = 0
      msg = '添加成功'
    } catch (error) {
      code = -1
      msg = '新建失败'
    }
  }
  ctx.body = {
    code,
    msg
  }
})

router.post('/del',async (ctx)=>{
  let code = 0 // 状态码
  let msg = '' // 返回内容
  let ret = await delUser(ctx.request.body)
  console.log(ret);

  if(ret){
    ctx.body = {
      code,
      msg:'删除成功'
    }
  }
  else {
    ctx.body = {
      code:-1,
      msg:'参数错误'
    }
  }
})
module.exports = router

• 在当前controller目录下新建增删改查工具方法，tools.js

// 导入schama
const Users = require('../dbs/schema/Users.js').Users
/* 查所有用户 */
exports.findAllUsers = async (params) => {
  let keyword = params.keyword ||'' ;
  const reg = new RegExp(keyword, 'i') //不区分大小写
  // 模糊查询
  let _filter = {
    userStatus:1,
    $or:[
      {
        userName:{$regex :reg}
      }
    ]
  }
  let count = 0
  count = await Users.countDocuments(_filter)

  let ret = await Users.find(_filter).limit(20)
  let _list = ret.map(v=>{
    return {
      username:v.userName,
      gender:v.gender,
      createAt:v.createAt,
      lastLoginAt:v.lastLoginAt,
    }
  })
  return {
    count,
    list:_list
  }

};
/* 查单个用户 */
exports.findOne = async (params) => {
  let ret = await Users.findOne({_id:params.id})
  let info = {
    id:ret._id,
    userName:ret.userName,
    createAt:ret.createAt,
    lastLoginAt:ret.lastLoginAt,
    gender:ret.gender
  }
  return {
    info
  }
};
/* 新增用户 */
exports.addUser = async (userParams) => {
  console.log('add=');
  console.log(userParams);
  return await userParams.save();
};

/**
 * 编辑
 */
exports.updateUser = async (userParams)=>{
  console.log('edit=');
  console.log(userParams);

  return await Users.updateOne({_id:userParams.id},{
    $set:{
      userName:userParams.userName,
      password:userParams.password,
      gender:userParams.gender
    }
  })
}

/**
 * 硬删除
 */
exports.removeUser = async (userParams)=>{
  return await Users.findOneAndRemove({_id:userParams.id})
}
/**
 * 软删除
 */
exports.delUser = async (userParams)=>{
  return await Users.findOneAndUpdate({_id:userParams.id},{userStatus:0})
}

• 运行代码：配置package.json，scripts新增"dev": "nodemon node ./app.js"

• 运行：npm run dev

• loacahost:4000/user/list获取列表

• loacahost:4000/user/detail获取用户详情

• loacahost:4000/user/addUser新增用户

• loacahost:4000/user/del删除用户