Convert Object to/from JSON in Rest API in Express


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

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 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 = {
    find: function (request, response) {
        response.setHeader('Content-Type', 'application/json');
        var product = {
            id: 'p01',
            name: 'name 1',
            price: 20
        };
        response.json(product);
    }
};

module.exports = DemoAPI;




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/find', DemoAPI.find);

module.exports = router;

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)
 });

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

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

Output

{"id":"p01","name":"name 1","price":20}

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

Use the following command to install http module

npm install http --save




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 = {
    find: function (callback) {
        return http.get(BASE_URL + 'demo/find', 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;

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.find(function (result) {
    if (result.error) {
        console.log(result.error)
    } else {
        console.log('Status: ' + result.status);
        console.log('Product Info');
        console.log('Id: ' + result.body.id);
        console.log('Name: ' + result.body.name);
        console.log('Price: ' + result.body.price);
    }
});




Status: 200

Product Info
Id: p01
Name: name 1Price: 20