Reusable Node Code Modules, Part 2 - Request Validation

Ensuring Data Integrity: Building Robust Request Validation Modules

Request validation is crucial for ensuring that incoming data meets specific criteria before processing it. Proper validation helps prevent errors, enhances security, and improves data integrity. This guide covers how to structure reusable request validation modules in Node.js and Express, manage validations efficiently, and integrate common libraries

Common Libraries and Tools

1. Joi

Joi is a powerful schema description language and data validator for JavaScript

Key Features

• Schema-based validation

• Rich validation rules

• Custom error messages

• Integration with Express

2. express-validator

express-validator is a set of Express.js middleware for validating and sanitizing user input

Key Features

• Declarative validation syntax

• Built-in sanitization

• Custom validators and sanitizers

• Integration with Express

3. Yup

Yup is a JavaScript schema builder for value parsing and validation

Key Features

• Schema-based validation

• Asynchronous validation support

• Custom validation methods

• Integration with various frameworks

4. Validator.js

Validator.js is a library for string validation and sanitization

Key Features

• Comprehensive string validation

• Built-in sanitization functions

• Lightweight and flexible

• Integration with other libraries

Comparison

• Joi: Best for schema-based validation with rich validation rules and custom error messages

• express-validator: Ideal for applications using Express, providing middleware for validation and sanitization

• Yup: Suitable for schema-based validation with asynchronous support and custom methods

• Validator.js: Best for lightweight string validation and sanitization

Examples

Example 1: Joi

Setup:

$ npm install joi

Middleware:

const Joi = require('joi');

const validateRequest = (schema) => (req, res, next) => {
  const { error } = schema.validate(req.body);
  if (error) {
    return res.status(400).json({ error: error.details[0].message });
  }
  next();
};

module.exports = validateRequest;

Usage:

const express = require('express');
const validateRequest = require('./validateRequest');
const Joi = require('joi');

const userSchema = Joi.object({
  name: Joi.string().min(3).required(),
  email: Joi.string().email().required(),
  password: Joi.string().min(6).required(),
});

const app = express();
app.use(express.json());

app.post('/register', validateRequest(userSchema), (req, res) => {
  res.send('User registered successfully');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Example 2: express-validator

Setup:

$ npm install express-validator

Middleware:

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

const validateRequest = (schema) => [
  checkSchema(schema),
  (req, res, next) => {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({ errors: errors.array() });
    }
    next();
  },
];

module.exports = validateRequest;

Usage:

const express = require('express');
const validateRequest = require('./validateRequest');

const userSchema = {
  name: {
    in: ['body'],
    isString: true,
    isLength: {
      options: { min: 3 },
    },
    errorMessage: 'Name must be at least 3 characters long',
  },
  email: {
    in: ['body'],
    isEmail: true,
    errorMessage: 'Invalid email address',
  },
  password: {
    in: ['body'],
    isString: true,
    isLength: {
      options: { min: 6 },
    },
    errorMessage: 'Password must be at least 6 characters long',
  },
};

const app = express();
app.use(express.json());

app.post('/register', validateRequest(userSchema), (req, res) => {
  res.send('User registered successfully');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Example 3: Yup

Setup:

$ npm install yup

Middleware:

const yup = require('yup');

const validateRequest = (schema) => async (req, res, next) => {
  try {
    await schema.validate(req.body);
    next();
  } catch (error) {
    res.status(400).json({ error: error.message });
  }
};

module.exports = validateRequest;

Usage:

const express = require('express');
const validateRequest = require('./validateRequest');
const yup = require('yup');

const userSchema = yup.object().shape({
  name: yup.string().min(3).required('Name is required'),
  email: yup.string().email('Invalid email').required('Email is required'),
  password: yup.string().min(6, 'Password must be at least 6 characters long').required('Password is required'),
});

const app = express();
app.use(express.json());

app.post('/register', validateRequest(userSchema), (req, res) => {
  res.send('User registered successfully');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Example 4: Validator.js

Setup:

$ npm install validator

Middleware:

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

const validateRequest = (schema) => [
  ...schema,
  (req, res, next) => {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({ errors: errors.array() });
    }
    next();
  },
];

module.exports = validateRequest;

Usage:

const express = require('express');
const validateRequest = require('./validateRequest');
const { body } = require('express-validator');

const userSchema = [
  body('name').isString().isLength({ min: 3 }).withMessage('Name must be at least 3 characters long'),
  body('email').isEmail().withMessage('Invalid email address'),
  body('password').isString().isLength({ min: 6 }).withMessage('Password must be at least 6 characters long'),
];

const app = express();
app.use(express.json());

app.post('/register', validateRequest(userSchema), (req, res) => {
  res.send('User registered successfully');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});