Express Form Validation: How to Make Form Validation in Node JS?

Aug 24, 2022

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Express Form Validation: How to Make Form Validation in Node JS?

Hi friends,

In this short tutorial we will cover an express form validation example. you will learn node js express form validation example. it's a simple example of node js express validation example. you will learn nodejs express form validation example. Let's see below example node js express validation example.

In this blog post, we will understand how to use the express-validator module to make the input validation from the server side. You will do so by completing a demo application that takes in user input and validates/sanitizes it using this library. Express Validator is a set of Express. js middleware that wraps validator. js, a library that provides validator and sanitizer functions. I will show you a simple example step-by-step explain.

let's see below simple example with output:

Step 1: Install Node JS


This step create express input validation project folder for by running the below command.

mkdir express-node-form-validation

Get inside the project directory.

cd express-node-form-validation

Step 2: Run command to create package.json:

npm init

Then now install nodemon module with --save-dev attribute for development purpose. This module takes care the server restarting process.

npm install nodemon --save-dev

Step 3: Install Express Validator Package

This step install following module from npm to build express and node app.

npm install body-parser cookie-parser cors express-session --save

Then after install implement input validation we need to install express and express-validator modules.

npm install express express-validator --save

Now see here is the final package.json file.

{

"name": "validation",

"version": "1.0.0",

"description": "Node JS Form Validation Example Tutorial",

"main": "app.js",

"scripts": {

"test": "node app.js"

},

"author": "piyush kamani",

"license": "ISC",

"devDependencies": {

"nodemon": "^2.0.19"

},

"dependencies": {

"body-parser": "^1.20.0",

"cookie-parser": "^1.4.6",

"cors": "^2.8.5",

"express": "^4.18.1",

"express-hbs": "^2.4.0",

"express-session": "^1.17.3",

"express-validator": "^6.14.2"

}

}

Step 4: Create app.js file

Here in this file we will keep node server settings.

Now, go to app.js file and include the following code in it.

app.js

const express = require('express');

const bodyParser = require('body-parser');

const cors = require('cors');

const cookieParser = require('cookie-parser');

const session = require('express-session');

// Express settings

const app = express();

app.use(bodyParser.json());

app.use(bodyParser.urlencoded({

extended: false

}));

app.use(cors());

app.use(cookieParser());

app.use(session({

secret: 'positronx',

saveUninitialized: false,

resave: false

}));

// Define PORT

const port = process.env.PORT || 8000;

const server = app.listen(port, () => {

console.log('Connected to port ' + port)

})

Step 5: Set Up Express Handlebars View Engine

we need to install express-hbs module, It’s a handlbars templating view engine.

Run below command to install the module.

npm install express-hbs --save

Then after create views folder inside the express input validation project folder.

Create partials folder within the views folder, following will be the folder architecture views/partials.

Step 6: Create user.hbs file

view/partials/user.hbs

<html lang="en">

<head>

<title>Node JS Express Form Data Validation - Nicesnippets.com</title>

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet">

</head>

<body>

<div class="container">

<div class="row justify-content-center">

<div class="col-md-8 text-center mt-5 mb-3">

<h3>Node JS Express Form Data Validation - Nicesnippets.com</h3>

</div>

<div class="col-md-8">

<form method="post" action="/user/create-user">

<div class="form-group">

<label>Name:</label>

<input type="text" class="form-control" name="name" />

</div>

<div class="form-group mt-2">

<label>Email:</label>

<input type="text" class="form-control" name="email" />

</div>

<div class="form-group mt-2">

<label>Password:</label>

<input type="password" class="form-control" name="password" />

</div>

<div class="form-group mt-2">

<label>Confirm Password:</label>

<input type="password" class="form-control" name="confirm_password" />

</div>

<div class="form-group mt-3">

<button type="submit" class="btn btn-success btn-block">Create</button>

</div>

</form>

</div>

</div>

</div>

</body>

</html>

Then add express handlebars view engine settings in app.js file.

// app.js

const hbs = require('express-hbs');

// Render View

app.engine('hbs', hbs.express4({

partialsDir: __dirname + '/views/partials'

}));

app.set('view engine', 'hbs');

app.set('views', __dirname + '/views/partials');

Run following URL and check the form in the browser:

http://localhost:8000/user

npm start

Form View:

Step 7: Implement Input Validation in Express Routes

In this step is create express routers to make the POST and GET requests using Express.js.

Create routes folder and create user.routes.js file inside paste the code.

routes/user.routes.js

const express = require("express");

const session = require('express-session');

const router = express.Router();

const { check, validationResult } = require('express-validator');

router.post('/create-user',

[

check('name')

.not()

.isEmpty()

.withMessage('Name is required'),

check('email', 'Email is required')

.isEmail(),

check('password', 'Password is requried')

.isLength({ min: 1 })

.custom((val, { req, loc, path }) => {

if (val !== req.body.confirm_password) {

throw new Error("Passwords don't match");

} else {

return value;

}

}),

], (req, res) => {

var errors = validationResult(req).array();

if (errors) {

req.session.errors = errors;

req.session.success = false;

res.redirect('/user');

} else {

req.session.success = true;

res.redirect('/user');

}

});

router.get('/', function (req, res) {

res.render('user', {

success: req.session.success,

errors: req.session.errors

});

req.session.errors = null;

});

module.exports = router;

Then go to app.js and add the express user router.

app.js

// User router

const user = require('./routes/user.routes');

// Initiate API

app.use('/user', user)

Step 8: Show Server-Side Validation Errors in Node App

Open your user.hbs add the following code in it.

view/partials/user.hbs

<html lang="en">

<head>

<title>Node JS Express Form Data Validation - Nicesnippets.com</title>

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet">

</head>

<body>

<div class="container">

<div class="row justify-content-center">

<div class="col-md-8 text-center mt-5 mb-3">

<h3>Node JS Express Form Data Validation - Nicesnippets.com</h3>

</div>

<div class="col-md-8">

{{# if errors }}

{{# each errors }}

<p class="alert alert-danger">{{ this.msg }}</p>

{{/each}}

{{/if}}

<form method="post" action="/user/create-user">

<div class="form-group">

<label>Name:</label>

<input type="text" class="form-control" name="name" />

</div>

<div class="form-group mt-2">

<label>Email:</label>

<input type="text" class="form-control" name="email" />

</div>

<div class="form-group mt-2">

<label>Password:</label>

<input type="password" class="form-control" name="password" />

</div>

<div class="form-group mt-2">

<label>Confirm Password:</label>

<input type="password" class="form-control" name="confirm_password" />

</div>

<div class="form-group mt-3">

<button type="submit" class="btn btn-success btn-block">Create</button>

</div>

</form>

</div>

</div>

</div>

</body>

</html>

Step 9: Run following Command Node App:

node app.js

Run following URL and check the form in the browser:

http://localhost:8000/user

Error Form View:

Output:

I hope it can help you...

#Node.js Express

#Node JS