How to Validate Data using express-validator Module in Node.js ?
Validation in node.js can be easily done by using the express-validator module. This module is popular for data validation. There are other modules available in market like hapi/joi, etc but express-validator is widely used and popular among them.
Steps to install express-validator module:
- You can install this package by using this command.
npm install express-validator
- After installation, you can check your express-validator module version in command prompt using the command.
npm version express-validator
- After that, you can just create a simple data as shown below to send the data to the server.
Filename: SampleForm.ejs
html
<!DOCTYPE html><html> <head> <title>Validation using Express-Validator</title> </head><body><h1>Demo Form</h1> <form action="saveData" method="POST"> <pre> Enter your Email : <input type="text" name="email"> <br> Enter your Name : <input type="text" name="name"> <br> Enter your Number : <input type="number" name="mobile"> <br> Enter your Password : <input type="password" name="password"> <br> <input type="submit" value="Submit Form"> </pre></form> </body></html> |
- After that, you can just create a file, for example index.js as show below:
Filename: index.js
javascript
const { check, validationResult } = require('express-validator');const bodyparser = require('body-parser')const express = require("express")const path = require('path')const app = express()var PORT = process.env.port || 3000// View Engine Setupapp.set("views", path.join(__dirname))app.set("view engine", "ejs")// Body-parser middlewareapp.use(bodyparser.urlencoded({ extended: false }))app.use(bodyparser.json())app.get("/", function (req, res) { res.render("SampleForm");})// check() is a middleware used to validate// the incoming data as per the fieldsapp.post('/saveData', [ check('email', 'Email length should be 10 to 30 characters') .isEmail().isLength({ min: 10, max: 30 }), check('name', 'Name length should be 10 to 20 characters') .isLength({ min: 10, max: 20 }), check('mobile', 'Mobile number should contains 10 digits') .isLength({ min: 10, max: 10 }), check('password', 'Password length should be 8 to 10 characters') .isLength({ min: 8, max: 10 })], (req, res) => { // validationResult function checks whether // any occurs or not and return an object const errors = validationResult(req); // If some error occurs, then this // block of code will run if (!errors.isEmpty()) { res.json(errors) } // If no error occurs, then this // block of code will run else { res.send("Successfully validated") }});app.listen(PORT, function (error) { if (error) throw error console.log("Server created Successfully on PORT ", PORT)}) |
Steps to run the program:
- The project structure will look as shown below:
- Make sure you have a ‘view engine’. We have used “ejs” and also install express and express-validator, body-parser using following commands:
npm install ejs
npm install express
npm install body-parser
npm install express-validator
- Run index.js file using below command:
node index.js
- Open the browser and type this URL http://localhost:8080/, the fill this sample form with correct data as shown below:
- Then submit the form and if no error occurs, then you will see the following output:
- And if you try to submit the form with incorrect data, then you will see the error message as shown below:
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