Introduction to Revalidator

Revalidator is a powerful schema validation tool for JavaScript objects, commonly used in Node.js applications. This library allows developers to define validation schemas and verify the objects against these predefined rules. In this guide, we will explore various API functionalities of Revalidator, providing detailed explanations and code snippets to illustrate their usage effectively.

Key APIs of Revalidator

Below are some of the vital APIs provided by the Revalidator library, explained with examples for a clear understanding:

1. Schema Definition

Define a schema to specify the validation rules for your data objects. The schema defines the structure of objects and the constraints.

 const revalidator = require('revalidator');

 const personSchema = {
   properties: {
     name: {
       description: 'Person\'s full name',
       type: 'string',
       required: true
     },
     age: {
       description: 'Person\'s age',
       type: 'integer',
       minimum: 0,
       maximum: 120,
       required: true
     },
     email: {
       description: 'Person\'s email address',
       type: 'string',
       format: 'email',
       required: true
     }
   }
 };

2. Validation API

Use the validate function to check objects against the predefined schema.

 const person = {
   name: 'John Doe',
   age: 28,
   email: 'john.doe@example.com'
 };

 const validation = revalidator.validate(person, personSchema);

 if (!validation.valid) {
   console.log(validation.errors);
 } else {
   console.log('Validation passed!');
 }

3. Validator Options

Customize the behavior of the validator using various available options.

 const options = {
   additionalProperties: false,
   cast: true
 };

 const validationWithOpts = revalidator.validate(person, personSchema, options);

Practical Application Example

Let’s see a practical example where a Node.js application validates user input data for a registration form using Revalidator:

 const express = require('express');
 const revalidator = require('revalidator');
 const app = express();

 const userSchema = {
   properties: {
     username: {
       description: 'Username for account',
       type: 'string',
       required: true,
       minLength: 3
     },
     password: {
       description: 'Password for account',
       type: 'string',
       required: true,
       minLength: 6
     },
     confirmPassword: {
       description: 'Confirm the password',
       type: 'string',
       required: true,
       minLength: 6
     },
     email: {
       description: 'Email address',
       type: 'string',
       format: 'email',
       required: true
     }
   }
 };

 app.use(express.json());

 app.post('/register', (req, res) => {
   const userData = req.body;
   const validation = revalidator.validate(userData, userSchema);

   if (!validation.valid) {
     return res.status(400).json({
       success: false,
       errors: validation.errors
     });
   }

   res.status(200).json({
     success: true,
     message: 'User registration successful!'
   });
 });

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

This example demonstrates how to use Revalidator for a user registration form, ensuring all required fields are properly validated before proceeding.

Conclusion: Revalidator is an essential library for validating JavaScript objects. By understanding and utilizing its various APIs, you can ensure that your data conforms to the expected schema and constraints, thus making your application more robust and error-free.

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