Top Examples of Validating User Input with Joi in Node.js

Introduction

Validating user input is a crucial step in web development, as it helps ensure that data received from users meets specific requirements before processing. Joi is a powerful schema description language for JavaScript that allows you to validate the shape and content of JavaScript objects. In this article, we will explore three diverse examples of validating user input with Joi in Node.js, showcasing its versatility and ease of use.

Example 1: Validating a User Registration Form

Context

This example demonstrates how to validate user input in a registration form. We will ensure that the username, email, and password meet specified criteria.

const Joi = require('joi');

const registrationSchema = Joi.object({
    username: Joi.string().alphanum().min(3).max(30).required(),
    email: Joi.string().email().required(),
    password: Joi.string().min(6).max(20).required()
});

const userInput = {
    username: 'user123',
    email: 'user@example.com',
    password: 'pass123'
};

const { error, value } = registrationSchema.validate(userInput);

if (error) {
    console.error('Validation error:', error.details);
} else {
    console.log('Validated user input:', value);
}

Notes

• The username must be alphanumeric and between 3 to 30 characters long.
• The email must follow a valid email format.
• The password must be between 6 to 20 characters long.

Example 2: Validating Product Data for an E-commerce Application

Context

In this example, we are validating input data for a new product in an e-commerce platform. The validation will ensure that all required fields are present and correctly formatted.

const Joi = require('joi');

const productSchema = Joi.object({
    name: Joi.string().min(3).max(100).required(),
    price: Joi.number().positive().required(),
    category: Joi.string().valid('electronics', 'clothing', 'books').required(),
    inStock: Joi.boolean().required()
});

const productData = {
    name: 'Wireless Headphones',
    price: 99.99,
    category: 'electronics',
    inStock: true
};

const { error, value } = productSchema.validate(productData);

if (error) {
    console.error('Validation error:', error.details);
} else {
    console.log('Validated product data:', value);
}

Notes

• The name must be between 3 to 100 characters.
• The price must be a positive number.
• The category must be one of the predefined options.
• The inStock field must be a boolean value.

Example 3: Validating a Comment Submission

Context

This example focuses on validating user comments submitted on a blog post. It ensures that the comment text is appropriate and includes the user’s name and email.

const Joi = require('joi');

const commentSchema = Joi.object({
    name: Joi.string().min(1).max(50).required(),
    email: Joi.string().email().required(),
    comment: Joi.string().min(5).max(500).required()
});

const commentInput = {
    name: 'John Doe',
    email: 'john.doe@example.com',
    comment: 'This is a great article!'
};

const { error, value } = commentSchema.validate(commentInput);

if (error) {
    console.error('Validation error:', error.details);
} else {
    console.log('Validated comment input:', value);
}

Notes

• The name must be between 1 to 50 characters.
• The email must follow a valid email format.
• The comment must be between 5 to 500 characters long.

By using Joi for validation in your Node.js applications, you can enhance the reliability and integrity of your data, resulting in a better user experience.