nodejs+Express+mongodb

One 、 Create project

// Install scaffolding 
$ npm install express-generator -g

// Create a project 
$ express -e demo( Project name )

// Load dependencies 
$ npm install

// Code real-time update （ Hot heavy load ）
$ npm install nodemon -g

(1). install nodemon after Need modification package.json Start command in

{
  "name": "mysql-demo",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    //"start": "node ./bin/www" // There will be  node  Change it to nodemon
    "start": "nodemon ./bin/www"
  },
  "dependencies": {
    "cookie-parser": "~1.4.4",
    "debug": "~2.6.9",
    "ejs": "~2.6.1",
    "express": "~4.16.1",
    "http-errors": "~1.6.3",
    "mongodb": "^4.1.3",
    "morgan": "~1.9.1",
    "nodemon": "^2.0.13"
  }
}

(2).nodemon Installation successful And modify the startup command perform   npm start start-up  

$ npm start

(3). Additional records start-up mongodb database install mongodb Self search  

// Specify the database directory   Directory address 
$ mongod --dbpath "D:\mongodb\data" 

// After startup   Open a new command line window   Create the database required for the project 
// perform   Linked database 
$ mongo

// Database basic command 
show db // View all databases 

user  Database name  // Enter the corresponding database （ There is no corresponding data to create ）

db.dropDatabase() // Delete database  （ You need to enter the corresponding database ）

db.createCollection("users") // create documents  " Document name " 

show collections // View all documents in the current database 

db.users.insertOne({name:'lory'}) // Insert a piece of data 

db.users.find() // View all data in the current document 

(4). install mongodb modular In the project file （demo） Folder command line window operation

$ npm install mongodb -s

(5). Create a new folder in the project after installation model Create a new... In this folder index.js file The content is

// establish mongo Client object 
const MongoClient = require('mongodb').MongoClient;
// database   Address 
const url = 'mongodb://localhost:27017';
// Database name 
const dbName = 'mongodb_demo'
//  Database link method encapsulation 
function connect(callback) {
    MongoClient.connect(url, function (err, client) {
        if (err) {
            console.log(' Database link error ', err)
        } else {
            let db = client.db(dbName)
            callback && callback(db)
        }
    })
}
module.exports = {
    connect
}

(6). After the above steps are completed, find routes Under folder index.js When the file is opened Modify the content

var express = require('express');
var router = express.Router();
// Introduce the encapsulated linked database method 
var model = require('../model')

/* GET home page. */
router.get('/', function (req, res, next) {
// Linked database 
  model.connect(function (db) {
// Find data in documents 
    db.collection('users').find().toArray(function (err, docs) {
      console.log(" User list ", docs)
      res.send({'msg':'S',data:docs}) // Interface to return 
      // res.render('index', { title: 'Express' }) // Templates 
    })
  })
});

module.exports = router;

(7). Write an interface （ Example ） stay routes Found in file users.js open Edit content

var express = require('express');
var router = express.Router();
// Introduce the encapsulated linked database method 
var model = require('../model')

/* GET users listing. */
router.get('/', function (req, res, next) {
  res.send({ 'msg': 'S', data: [] })
});

// Here is the added content   Each route can write multiple interfaces 
/*  register */
router.post('/regist', function (req, res, next) {
  let data = {
    username: req.body.username,
    password: req.body.password,
    password2: req.body.password2
  }
  if (!data.username) {
    res.send({ 'msg': ' Please fill in your name ', code: 201 })
    return
  }
  if (!data.password) {
    res.send({ 'msg': ' Please fill in the password ', code: 201 })
    return
  }
  if (data.password != data.password2) {
    res.send({ 'msg': ' Password inconsistency ', code: 201 })
    return
  }

  model.connect((db) => {
    db.collection('users').insertOne(data, (err, ret) => {
      if (err) {
        console.log(' Registration failed ')
        res.send({ 'msg': ' Registration failed ', code: 201 })
      } else {
        res.send({ 'msg': ' Registered successfully ', code: 200, data: data })
      }
    })
  })
});

module.exports = router;

(8). open app.js file stay  var app = express(); Add... After this line of code   To prevent cross domain during testing  

// Set up cross domain access 
app.all("*",function(req,res,next){
  // Set domain names that allow cross domain ,* Allows any domain name to cross domain 
  res.header("Access-Control-Allow-Origin","*");
  // Allow the header type 
  res.header("Access-Control-Allow-Headers","content-type");
  // How cross domain requests are allowed  
  res.header("Access-Control-Allow-Methods","DELETE,PUT,POST,GET,OPTIONS");
  if (req.method.toLowerCase() == 'options')
      res.send(200);  // Give Way options Try to request a quick end 
  else
      next();
})

(9). then Create a new front end html file （ Test interface ） The content is   After writing, open in the browser View console

<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
	</body>
	<script src="https://cdn.staticfile.org/jquery/3.5.1/jquery.min.js" type="text/javascript" charset="utf-8"></script>
	<script type="text/javascript">
		$(function() {
			$.ajax({
				type: "post",
				url: "http://localhost:3000/users/regist",
				data: {
					username: ' Liu Yi ',
					password: '123',
					password2: '123'
				},
				async: true,
				success: function(res) {
					console.log(res)
				}
			});
		})
	</script>

</html>

(10). Add route stay routes Add in folder .js file And then in app.js Add... To the file

// similar   Introduced in this way 
var usersRouter = require('./routes/users（ New file name ）');

app.use('/users'（ The path of the corresponding interface ）, usersRouter（ New file name ）);

This is probably the completion of There is a problem Self Baidu or leave a message

Two 、 The following record is a link mysql database

The above first 4 Step install mongodb modular Install... Instead mysql modular

$ npm install mysql

The code of step 5 above is changed to

// establish mysql Client object 
let mysql = require("mysql");

const db_config = {
    host: "localhost", // database ( The host address ) （ Default ：localhost）
    user: "root", // user name 
    password: "root",// password 
    port: "3000", // Port number 
    database: "testdb" // Database name 
}
let sql = mysql.createConnection(db_config);
//  Database link method encapsulation 
function connect(callback) {
    sql.connect(function (err) {
        if (err) {
            console.log(' Database link error ', err);
        } else {
            callback && callback(sql)
        }
    })
}

// Close after successful query mysql
function closeMysql(connect) {
    connect.end((err) => {
        if (err) {
            console.log(`mysql Close the failure :${err}!`);
        } else {
            console.log('mysql Closed successfully !');
        }
    });
}

// // Basic query statements 
// let sqlQuery = "select * from tb_user";
// sql.query(sqlQuery, function (err, result) {
//     if (err) {
//         console.log(`SQL error: ${err}!`);
//     } else {
//         console.log(result);
//         closeMysql(connect);
//     }
// });

module.exports = {
    connect,
    closeMysql
}

then routes Medium index.js Change the file to After modification open localhost:3000 see The rest modify the test yourself

var express = require('express');
var router = express.Router();
var model = require('../model')

/* GET home page. */
router.get('/', function (req, res, next) {
  // res.render('index', { title: 'Express' });
  // // Basic query statements 
  model.connect(function (db) {
    let sqlQuery = "select * from tb_user";
    db.query(sqlQuery, function (err, result) {
      if (err) {
        console.log(`SQL error: ${err}!`);
      } else {
        console.log(result);
        model.closeMysql(db);
      }
    });
  })

});

module.exports = router;