WebAPI Using NodeJS, Express, And MySQL

Introduction

In this article, we are going to create a Web API with the help of node.js, Express, and MySQL. Web API is an application which serves HTTP based requests by different applications on different platforms, such as web, Windows, and mobile.

Requirements

MySQL
NodeJS
Active Internet
Postman Application
Visual Studio Code

Step 1

Create a database in MySQL, named sampledb and use it.

mysql> create database sampledb;
mysql> use sampledb;

Step 2

Create a new table named employee.

mysql> create table employee
(
id int primary key,
name varchar(20),
gender varchar(20),
city varchar(20),
salary int
);

Step 3

Add some rows to the table.

mysql> insert into employee values(1,'pankaj','male','delhi',15000);
mysql> insert into employee values(2,'pooja','female','pune',25000);

Step 4

Open command prompt/cmd and navigate to the application folder, i.e., webapi.

C:\Users\Pankaj Singh\Desktop\webapi>

Step 5

Initialize the app with npm init,

C:\Users\Pankaj Singh\Desktop\webapi>npm init

Step 6

Now, add some Node modules, as mentioned below.

C:\Users\Pankaj Singh\Desktop\webapi>npm install express

C:\Users\Pankaj Singh\Desktop\webapi>npm install mysql

C:\Users\Pankaj Singh\Desktop\webapi>npm install body-parser

Step 7

Add a server.js file to the application.

C:\Users\Pankaj Singh\Desktop\webapi>null>server.js

Step 8

Open Visual Studio Code.

C:\Users\Pankaj Singh\Desktop\webapi>code .

Step 9

Our package.json file looks like this.

Step 10

Now, configure the server.js file. Basic Express app is as follows

var express = require('express');
var mysql = require('mysql');
var bodyParser=require('body-parser');
var urlencoderParser = bodyParser.urlencoded({extended:false});
var app=express();
var port = process.env.port||3000;
//Api code here
app.listen(port);
console.log('Server is started on http://localhost:'+port);

Step 11

Add a connection to MySQL.

//Mysql Connection
var con = mysql.createConnection({
host:'localhost',
user:'root',
password:'password0',
database:'sampledb'
});

Step 12

Now, add code for GET request on root “/api” . This route returns all the rows of employee table.

//GET
app.get('/api',function(req,res){
var qry = "select * from employee";
con.query(qry,function(err,rows){
if(err)
throw err;
console.log(rows);
res.json(rows);
});
});

Step 13

Add code for GET request with id on root “/api/<id>”. This route returns the row of employee table with the given id

//GET with id
app.get('/api/:id',function(req,res){
var qry = "select * from employee where id="+req.params.id;
con.query(qry,function(err,rows){
if(err)
throw err;
console.log(rows[0]);
res.json(rows[0]);
});
});

Step 14

Now, add code for POST request. In this request, we use urlencoderParser to read the body content of the request.

//POST
app.post('/api',urlencoderParser,function(req,res){
var qry = "insert into employee values("+parseInt(req.body.id)+",'"+req.body.name+"','"+req.body.gender+"','"+req.body.city+"',"+parseInt(req.body.salary)+")";
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Added.");
res.send("1 Row Added.")
});
});

Step 15

Now, add code for POST request. In this request, we use urlencoderParser to read the body content of the request.

//PUT
app.put('/api/:id',urlencoderParser,function(req,res){
var qry = "update employee set name='"+req.body.name+"',gender='"+req.body.gender+"',city='"+req.body.city+"',salary="+parseInt(req.body.salary)+" where id="+parseInt(req.params.id);
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Updated.");
res.send("1 Row Updated.")
});
});

Step 16

Add the code for DELETE Request.

//DELETE
app.delete('/api/:id',function(req,res){
var qry = "delete from employee where id="+parseInt(req.params.id);
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Removed.");
res.send("1 Row Removed.")
});
});

Step 17

The complete code is as follows.

var express = require('express');
var mysql = require('mysql');
var bodyParser=require('body-parser');
var urlencoderParser = bodyParser.urlencoded({extended:false});
var app=express();
var port = process.env.port||3000;
//Api code here
//Mysql Connection
var con = mysql.createConnection({
host:'localhost',
user:'root',
password:'password0',
database:'sampledb'
});
//GET
app.get('/api',function(req,res){
var qry = "select * from employee";
con.query(qry,function(err,rows){
if(err)
throw err;
console.log(rows);
res.json(rows);
});
});
//GET with id
app.get('/api/:id',function(req,res){
var qry = "select * from employee where id="+req.params.id;
con.query(qry,function(err,rows){
if(err)
throw err;
console.log(rows[0]);
res.json(rows[0]);
});
});
//POST
app.post('/api',urlencoderParser,function(req,res){
var qry = "insert into employee values("+parseInt(req.body.id)+",'"+req.body.name+"','"+req.body.gender+"','"+req.body.city+"',"+parseInt(req.body.salary)+")";
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Added.");
res.send("1 Row Added.")
});
});
//PUT
app.put('/api/:id',urlencoderParser,function(req,res){
var qry = "update employee set name='"+req.body.name+"',gender='"+req.body.gender+"',city='"+req.body.city+"',salary="+parseInt(req.body.salary)+" where id="+parseInt(req.params.id);
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Updated.");
res.send("1 Row Updated.")
});
});
//DELETE
app.delete('/api/:id',function(req,res){
var qry = "delete from employee where id="+parseInt(req.params.id);
con.query(qry,function(err,rows){
if(err)
throw err;
console.log("1 Row Removed.");
res.send("1 Row Removed.")
});
});
app.listen(port);
console.log('Server is started on http://localhost:'+port);