light-express-validator

light-express-validator is a homemade lightweight validation middleware for Express.js applications. It allows you to easily validate incoming request data with a simple and intuitive syntax.

1. Why light express validator?

- It's simple to use, lightweight and 0 dependency.

Installation

To install the package, run:

``
npm install light-express-validator
`

Usage

$3

1. First, require the package in your Express.js application:

`javascript
const validate = require('light-express-validator');
`

2. Define your validation rules for each field you want to validate:

`javascript
const validationRules = {
username: 'required|min:3|max:20',
email: 'required|email',
age: 'required|numeric|min:18',
};
`

3. Use the validate middleware in your route:

`javascript
app.post('/user', validate(validationRules), (req, res) => {
// Your route handler logic here
});
`

$3

- required: Field must be present and not empty
- min:x: Field must have a minimum of x characters
- max:x: Field must have a maximum of x characters
- numeric: Field must be a number
- integer: Field must be an integer
- decimal:x: Field must be a decimal with x decimal places
- boolean: Field must be true or false
- date: Field must be a valid date
- email: Field must be a valid email
- image: Field must be an image file (for file uploads)

$3

If validation fails, the middleware will automatically send a 400 Bad Request response with detailed error information. The response will have this structure:

`json
{
"name": "ValidationError",
"fields": {
"name": "The name field must be at most 9 characters.",
"email": "The email field must be a valid email address."
}
}
`

$3

If you want to handle validation errors differently, you can catch the ValidationError:

`javascript
app.use((err, req, res, next) => {
if (err instanceof ValidationError) {
// Custom error handling logic
return res.status(422).json({ errors: err.fields });
}
next(err);
});
`

Example

Here's a complete example of how to use light-express-validator in an Express.js route:

`javascript
const express = require('express');
const validate = require('light-express-validator');

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

app.post(
'/user',
validate({
username: 'required|min:3|max:20',
email: 'required|email',
age: 'required|numeric',
}),
(req, res) => {
// If we reach here, validation passed
res.json({ message: 'User created successfully', user: req.body });
}
);

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

This setup will validate that:

- username is required, at least 3 characters, and no more than 20 characters
- email is required and a valid email format
- age` is required, numeric

If any of these validations fail, it will return a 400 Bad Request with details about which fields failed validation.