How create RestFull API using Node.Js and expressJs from Scratch?

REST stands for REpresentational State Transfer. REST is web standards based architecture and uses HTTP Protocol. It is an architectural style as well as an approach for communications purposes that is often used in various web services development. A REST Server simply provides access to resources and REST client accesses and modifies the resources using HTTP protocol.

HTTP methods:

• GET − Provides read-only access to a resource.
• PUT − Updates an existing resource or creates a new resource.
• DELETE − Removes a resource.
• POST − Creates a new resource.
• PATCH− Update/modify a resource

Example:

// users.json
{
   "user1" : {
      "id": 1,
      "name" : "Ehsan Philip",
      "age" : 24
   },

   "user2" : {
      "id": 2,
      "name" : "Karim Jimenez",
      "age" : 22
   },

   "user3" : {
      "id": 3,
      "name" : "Giacomo Weir",
      "age" : 18
   }
}

List Users ( GET method)

Let's implement our first RESTful API listUsers using the following code in a server.js file −

var express = require('express');
var app = express();
var fs = require("fs");

app.get('/listUsers', function (req, res) {
   fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
      console.log( data );
      res.end( data );
   });
})

var server = app.listen(3000, function () {
   var host = server.address().address
   var port = server.address().port
   console.log("App listening at http://%s:%s", host, port)
});

Add User ( POST method )

Following API will show you how to add new user in the list.

var express = require('express');
var app = express();
var fs = require("fs");

var user = {
   "user4" : {
      "id": 4,
      "name" : "Spencer Amos",
      "age" : 28
   }
}

app.post('/addUser', function (req, res) {
   // First read existing users.
   fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
      data = JSON.parse( data );
      data["user4"] = user["user4"];
      console.log( data );
      res.end( JSON.stringify(data));
   });
})

var server = app.listen(3000, function () {
   var host = server.address().address
   var port = server.address().port
   console.log("App listening at http://%s:%s", host, port)
})

Delete User:

var express = require('express');
var app = express();
var fs = require("fs");

var id = 2;

app.delete('/deleteUser', function (req, res) {
   // First read existing users.
   fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
      data = JSON.parse( data );
      delete data["user" + 2];
      console.log( data );
      res.end( JSON.stringify(data));
   });
})

var server = app.listen(3000, function () {
   var host = server.address().address
   var port = server.address().port
   console.log("App listening at http://%s:%s", host, port)
})