Convert Object List to/from JSON in Rest API in Express

Create Server Project

Create LearnExpressJSRestAPIWithRealApps folder and select to this folder in Visual Studio Code

Install Express.JS

Use the following command to install Express.JS:

npm install express --save
npm install body-parser --save
npm install cookie-parser --save
npm install multer --save

Create Rest API

Create a new folder named api inside the server project. Create demo.api.js file inside api folder contains Rest APIs provides application/json data for the client

var DemoAPI = {
    findAll: function (request, response) {
        response.setHeader('Content-Type', 'application/json');
        var products = [
            {
                id: 'p01',
                name: 'name 1',
                price: 20
            },
            {
                id: 'p02',
                name: 'name 2',
                price: 21
            },
            {
                id: 'p03',
                name: 'name 3',
                price: 22
            }
        ];
        response.json(products);
    }
};

module.exports = DemoAPI;

Create Rest API Routing

Inside the api folder create a new file named index.js. This file will hold all the routes needed for rest api in server.

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

var DemoAPI = require('./demo.api');

router.get('/demo/findAll', DemoAPI.findAll);

module.exports = router;

Create Rest API Server

At the root of server project, create a file named server.js. This will be the entry point into node application. This will start the server and listen on a local port

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

app.use('/api', require('./api/index'));

var server = app.listen(9090, function () {
	var host = server.address().address;
	var port = server.address().port;
	console.log("Server listening at http://%s:%s", host, port)
 });

Structure of Server Project

Test Rest API Server

At the root of server project run command: node server.js

Access Rest API use the following url: http://localhost:9090/api/demo/findAll

Output

[
    {"id":"p01","name":"name 1","price":20},
    {"id":"p02","name":"name 2","price":21},
    {"id":"p03","name":"name 3","price":22}
]

Create Client Project

Create LearnExpressJSRestAPIWithRealApps_Client folder and select to this folder in Visual Studio Code

Install Modules

Use the following command to install http module

npm install http --save

Create Demo Rest API Client

Create a new folder named api inside the client folder. Create demo.api.js file inside api folder contains method call Rest API from server

var http = require('http');
var BASE_URL = 'http://localhost:9090/api/';

var DemoAPIClient = {
    findAll: function (callback) {
        return http.get(BASE_URL + 'demo/findAll', function (response) {
            var str = '';
            response.on('data', function (chunk) {
                str += chunk;
            });
            response.on('end', function () {
                callback({
                    status: response.statusCode,
                    body: JSON.parse(str)
                });
            });
            response.on('error', function (error) {
                callback({
                    status: response.statusCode,
                    error: error.message
                });
            });
        }).end();
    }
};

module.exports = DemoAPIClient;

Structure of Client Project

Test Client Project

At the root of client project, create a file named client.js. This will call Rest API and display results

var DemoAPIClient = require('./api/demo.api');

DemoAPIClient.findAll(function (result) {
    if (result.error) {
        console.log(result.error)
    } else {
        console.log('Status: ' + result.status);
        console.log('Products List');
        console.log('Size: ' + result.body.length);
        for (var i = 0; i < result.body.length; i++) {
            console.log('Id: ' + result.body[i].id);
            console.log('Name: ' + result.body[i].name);
            console.log('Price: ' + result.body[i].price);
            console.log('===========================');
        }
    }
});

Output

Status: 200

Products List
Size: 3
Id: p01
Name: name 1
Price: 20
===========================
Id: p02
Name: name 2
Price: 21
===========================
Id: p03
Name: name 3
Price: 22
===========================