Node.js（六）MongoDB

student.js

var express = require('express');

var router = express.Router();

const _=require("lodash");

const { MongoClient } = require("mongodb");  //依赖MongoClient

var client=new MongoClient("mongodb://127.0.0.1:27017");  //实例化一个客户端

var clientAdd=new MongoClient("mongodb://127.0.0.1:27017");  //实例化一个客户端

var clientdel=new MongoClient("mongodb://127.0.0.1:27017");  //实例化一个客户端

var books=[];

//查询全部

async function run(){

  try{

      let db=await client.db("BookMessge"); //获取数据库

      let students=await db.collection("books");  //获取集合

      let cursor=await students.find();  //执行查询并返回游标对象

      await cursor.forEach(data=>books.push(data));  //遍历游标，取出数据

  }

  finally{

      await client.close();  //关闭

  }

};

//添加

async function add(booklist){

  try{

      let db=await clientAdd.db("BookMessge");  //获取数据库

      let students=await db.collection("books");  //获取集合，表

      let result=await students.insertOne(booklist);  //执行向数据库中添加数据并等待响应结果

      console.log(result);

  }

  finally{

      await clientAdd.close();  //关闭数据库

  }

}

//删除

async function del(id){

  try{

      let db=await clientdel.db("BookMessge");  //获取数据库

      let students=await db.collection("books");  //获取集合，表

      let result= await students.deleteOne(id);  //执行删除

      console.log(result);

  }

  finally{

      await clientdel.close();  //关闭

  }

}

run().catch(console.log);

/* GET home page. */

router.get('/', function(req, res, next) {

  res.render('student', {books,msg: '',stu:{id:"",name:"",age:""}});

});

router.get('/delete/:id', function(req, res, next) {

  //查找选中id的索引

  let id=req.params.id;

  console.log(id);

  let ids={id:""};

  ids.id=id;

  console.log(ids);

  del(ids).catch(console.log);

  res.render('student', {books,msg: '删除成功！',stu:{id:"",name:"",age:""}});

});

//添加

router.post('/add', function(req, res, next) {

  //查找选中id的索引

  let book=req.body;

  //根据编号排序

  let new_id=_.orderBy(books,parseInt(["id"]));

  book.id=_.last(new_id).id+1;

  //拿到序号

  let newbooks_id=_.orderBy(books,parseInt(["books_id"]));

  book.books_id=_.last(newbooks_id).books_id+1;

  console.log(book);

  add(book).catch(console.log);

  res.render('student', {books,msg: '添加成功'});

});

//修改

router.get('/edit/:id', function(req, res, next) {

  //查找选中id的索引

  let stu=_.find(stus,{id:parseInt(req.params.id)})

  console.log(stus);

  res.render('student', {stus,msg: '',stu});

});

//更新

router.post('/update', function(req, res, next) {

  //查找选中id的索引

  let stuSubmit=req.body;

  let stu=_.find(stus,{id:parseInt(stuSubmit.id)})

  stu.name=stuSubmit.name;

  stu.age=stuSubmit.age;

  //重新渲染页面

  res.render('student', {stus,msg: '更新成功',stu:{id:"",name:"",age:""}});

});

module.exports = router;

student.ejs

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge">

    <meta name="viewport" content="width=device-width, initial-scale=1.0">

    <title>图书管理系统</title>

</head>

<body>

    <h1>图书管理系统</h1>

    <table width="100%" border="1">

        <tr>

            <th>序号</th>

            <th>编号</th>

            <th>书名</th>

            <th>封面</th>

            <th>价格</th>

            <th>作者</th>

            <th>操作</th>

        </tr>

        <% for(let i=0;i<books.length;i++){ %>

            <tr style="text-align: center;">

                <td><%=books[i].id%></td>

                <td><%=books[i].books_id%></td>

                <td><%=books[i].name%></td>

                <td><%=books[i].img%></td>

                <td><%=books[i].price%></td>

                <td><%=books[i].author%></td>

                <td>

                    <a href="/delete/<%=books[i].id%>" class="del">删除</a>

                    <a href="/edit/<%=books[i].id%>">修改</a>

                </td>

            </tr>

        <%} %>

    </table>

    <fieldset>

        <legend>添加学生</legend>

        <form method="post">

            <input type="hidden" name="id" id="id" value="<%=books.id%>">

            <input type="hidden" name="books_id" id="books_id" value="<%=books.books_id%>">

            <p>

                <label>图书名称：</label>

                <input type="text" name="name" value="<%=books.name%>">

            </p>

            <p>

                <label>图书封面：</label>

                <input type="file" name="img" value="<%=books.img%>">

            </p>

            <p>

                <label>图书价格：</label>

                <input type="text" name="price" value="<%=books.price%>">

            </p>

            <p>

                <label>图书作者：</label>

                <input type="text" name="author" value="<%=books.author%>">

            </p>

            <button formaction="/add">添加</button>

            <button formaction="/update">更新</button>

        </form>

    </fieldset>

    <h4><%=msg%></h4>

    <script>

      let dels=document.querySelectorAll(".del");

      for(let i=0;i<dels.length;i++){

        dels[i].onclick=function(){

            return confirm("您确定要删除吗？");

        }

      }

    </script>

</body>

</html>

app.js

var createError = require('http-errors');

var express = require('express');

var path = require('path');

var cookieParser = require('cookie-parser');

var logger = require('morgan');

var indexRouter = require('./routes/index');

var usersRouter = require('./routes/users');

var studentRouter = require('./routes/student');

var app = express();

// view engine setup

app.set('views', path.join(__dirname, 'views'));

app.set('view engine', 'ejs');

app.use(logger('dev'));

app.use(express.json());

app.use(express.urlencoded({ extended: false }));

app.use(cookieParser());

app.use(express.static(path.join(__dirname, 'public')));

app.use('/index', indexRouter);

app.use('/users', usersRouter);

app.use('/', studentRouter);

// catch 404 and forward to error handler

app.use(function(req, res, next) {

  next(createError(404));

});

// error handler

app.use(function(err, req, res, next) {

  // set locals, only providing error in development

  res.locals.message = err.message;

  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page

  res.status(err.status || 500);

  res.render('error');

});

module.exports = app;

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Node.js（六）MongoDB

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