rsnext/docs/api-routes/api-middlewares.md

description
API Routes provide built-in middlewares that parse the incoming request. Learn more about them here.

API Middlewares

Examples

• API Routes with middleware
• API Routes with CORS

API routes provide built in middlewares which parse the incoming request (req). Those middlewares are:

• req.cookies - An object containing the cookies sent by the request. Defaults to {}
• req.query - An object containing the query string. Defaults to {}
• req.body - An object containing the body parsed by content-type, or null if no body was sent

Custom config

Every API route can export a config object to change the default configs, which are the following:

export const config = {
  api: {
    bodyParser: {
      sizeLimit: '1mb',
    },
  },
}

The api object includes all configs available for API routes.

bodyParser Enables body parsing, you can disable it if you want to consume it as a Stream:

export const config = {
  api: {
    bodyParser: false,
  },
}

bodyParser.sizeLimit is the maximum size allowed for the parsed body, in any format supported by bytes, like so:

export const config = {
  api: {
    bodyParser: {
      sizeLimit: '500kb',
    },
  },
}

Connect/Express middleware support

You can also use Connect compatible middleware.

For example, configuring CORS for your API endpoint can be done leveraging the cors package.

First, install cors:

npm i cors
# or
yarn add cors

Now, let's add cors to the API route:

import Cors from 'cors'

// Initializing the cors middleware
const cors = Cors({
  methods: ['GET', 'HEAD'],
})

// Helper method to wait for a middleware to execute before continuing
// And to throw an error when an error happens in a middleware
function runMiddleware(req, res, fn) {
  return new Promise((resolve, reject) => {
    fn(req, res, result => {
      if (result instanceof Error) {
        return reject(result)
      }

      return resolve(result)
    })
  })
}

async function handler(req, res) {
  // Run the middleware
  await runMiddleware(req, res, cors)

  // Rest of the API logic
  res.json({ message: 'Hello Everyone!' })
}

export default handler

Go to the API Routes with CORS example to see the finished app