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前言

Node.js是一个javascript运行环境。它让javascript可以开发后端程序，实现几乎其他后端语言实现的所有功能，可以与```PHP、Java、Python、.NET、Ruby等后端语言平起平坐。
Nodejs是基于V8引擎，V8是Google发布的开源JavaScript引擎，本身就是用于Chrome浏览器的JS解释，但是Node之父 Ryan Dahl把这V8搬到了服务器上，用于做服务器的软件。

MVC思想开发

服务器代码演示

const express = require('express');
const  router = express.Router();

//自定义模块
const UserController = require('../controllers/UserController');

router.get('/', function (req, res, next) {
  res.send('respond with a resource');
});

//相应前端的post请求-增加用户
router.post("/user", UserController.addUser)
//动态路由, 获取id -更新用户
router.put("/user/:myid", UserController.updateUser)
//删除用户
router.delete("/user/:id", UserController.deleteUser)
//获取用户列表
router.get("/user", UserController.getUser)

module.exports = router;

M层 Services 或 Model

代码演示

-----M UserService------

-----M UserService------
 //数据库Model层
const UserService = {
    addUser: (username, password, age) => {
        return UserModel.create({
            username, password, age
        })
    },

    updateUser: (_id, username, age, password) => {
        return UserModel.updateOne({ _id }, {
            username, age, password
        })
    },
    deleteUser: (_id) => {
        return UserModel.deleteOne({
            _id: _id
        })
    },
    getUser: (page, limit) => {
        return UserModel.find({}, ["username", "age"]).sort({ age: -1 }).skip((page - 1) * limit).limit(limit)
    }
}

module.exports = UserService

V层 Views

-----V UserView------

<!DOCTYPE html>
<html>

<head>
  <title>Login登录</title>
</head>

<body>
  <h1>mongodb的增删改查的演示</h1>
  <div>
    <div>用户名:<input id="username" /></div>
    <div>密码:<input type="password" id="password" /></div>
    <div>年龄:<input type="number" id="age" /></div>
    <div><button id="register">注册</button></div>
  </div>
  <hr>
  <div>
    <button id="update">更新</button>
    <button id="delete">删除</button>
  </div>
  <hr>

  <table border="1">
    <thead>
      <tr>
        <td>id</td>
        <td>用户名</td>
        <td>年龄</td>
      </tr>
    </thead>
    <tbody>

    </tbody>
  </table>
  <script>
    var register = document.querySelector("#register")
    var update = document.querySelector("#update")
    var deletebutton = document.querySelector("#delete")
    var username = document.querySelector("#username")
    var password = document.querySelector("#password")
    var age = document.querySelector("#age")

    register.onclick = () => {
      console.log(username.value, password.value, age.value)
      fetch("/api/user", {
        method: "POST",
        body: JSON.stringify({
          username: username.value,
          password: password.value,
          age: age.value
        }),
        headers: {
          "Content-Type": "application/json"
        }
      }).then(res => res.json()).then(res => {
        console.log(res)
      })
    }

    update.onclick = () => {
      fetch("/api/user/？", {
        method: "PUT",
        body: JSON.stringify({
          username: "修改的名字",
          password: "修改的密码",
          age: 1
        }),
        headers: {
          "Content-Type": "application/json"
        }
      }).then(res => res.json()).then(res => {
        console.log(res)
      })
    }

    deletebutton.onclick = () => {
      fetch("/api/user/？", {
        method: "DELETE"
      }).then(res => res.json()).then(res => {
        console.log(res)
      })
    }

    //获取列表
    fetch("/api/user?page=1&limit=10").then(res => res.json()).then(res => {
      var tbody = document.querySelector("tbody")
      tbody.innerHTML = res.map(item => `
          <tr>
            <td>${item._id}</td>  
            <td>${item.username}</td>  
            <td>${item.age}</td>  
          </tr>
        `).join("")
    })
  </script>
</body>

</html>

C层 Controllers

-----C UserCollection------

const UserService = require("../services/UserService") //导入数据层

const UserController = {
  addUser: async (req, res) => {
    //插入数据库
    const { username, password, age } = req.body
    
    await UserService.addUser(username, password, age)

    res.send({
      ok: 1
    })
  },

  updateUser: async (req, res) => {
    console.log(req.body, req.params.myid)
    const { username, age, password } = req.body
    
    await UserService.updateUser(req.params.myid, username, age, password)

    res.send({
      ok: 1
    })
  },
  deleteUser: async (req, res) => {
  
    await UserService.deleteUser(req.params.id)

    res.send({
      ok: 1
    })
  },

  getUser: async (req, res) => {
  
    const { page, limit } = req.query
    
    const data = await UserService.getUser(page, limit)

    res.send(data)
  }
}

module.exports = UserController