next-joi

Validate NEXT.js API Routes with joi 😄

- Install
- Getting started
- How does it work?
- Working with NEXT.js API Routes
- NEXT.js & connect-like middlewares
- API
- withJoi(config?) => validate
- config
- config.onValidationError
- validate(schemas, handler)
- schemas
- schemas.body
- schemas.headers
- schemas.query
- handler

Install

``
yarn add next-joi
`

This package does not bundle with next.js or joi, so you will need to install them separately.

Getting started

$3

The validation function will check the incoming request against the defined validation schemas. If the request does not comply with the schemas, it will be aborted immediately, and (by default) a 400 BAD REQUEST response will be returned. It is possible to customize this error handling by passing a custom onValidationError function to the primary factory function.

lib/middlewares/validation.ts

`ts
import withJoi from "next-joi";

export default withJoi({
onValidationError: (_, res) => {
return res.status(400).end();
},
});
`

$3

If you are using standard NEXT.js API Routes, you may use the validation function to wrap your route definition and pass
along the validation schema:

`ts
import Joi from "joi";

import validate from "/lib/middlewares/validation";

const schema = Joi.object({
birthdate: Joi.date().iso(),
email: Joi.string().email().required(),
name: Joi.string().required(),
});

export default validate({ body: schema }, (req, res) => {
// This function will be only executed if the incoming request complies
// with the validation schema defined above.
});
`

$3

If your routes are powered by using a package such as next-connect, you can still use next-joi!
The middleware function is ready to work with connect just out-of-the-box:

`ts
import Joi from "joi";
import connect from "next-connect";

import validate from "/lib/middlewares/validation";

const schema = Joi.object({
birthdate: Joi.date().iso(),
email: Joi.string().email().required(),
name: Joi.string().required(),
});

export default connect().post(validate({ body: schema }), (req, res) => {
// This function will be only executed if the incoming request complies
// with the validation schema defined above.
}))
`

API

$3

This factory function may optionally receive a configuration object. It will return the actual validation function (validate) that can be used as API route middleware.

#### config

Optional

If omitted, next-joi will use a default configuration.

##### config.onValidationError

Required

Custom error function to handle validation errors. It will receive the API request, response, and validation error.

`ts
import withJoi from "next-joi";

export default withJoi({
onValidationError: (req, res, error) => {
return res.status(400).end();
},
});
`

$3

The validate function has support to check the following request fields: body, headers and query. The first argument for this function should always be an object with the desired validation schemas.

#### schemas

Required

Even if empty, this argument is required.

##### schemas.body

Optional

A valid joi schema.

##### schemas.headers

Optional

> Note: since most of the time, you may receive more headers than expected, it is a good practice to make this
> schema always support unknown keys. Otherwise, the validation
> will fail.

A valid joi schema.

##### schemas.query

Optional

A valid joi schema.

#### handler

Optional

A valid next API Route handler. If you are using the validate function without a connect-like middleware engine, this argument becomes mandatory.

Example:

`ts
const handler = function (req: NextApiRequest, res: NextApiResponse) {
// implementation
};

export default validate({}, handler);
``