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next-connect v0.8.1

The method routing and middleware layer for Next.js (and several others)

next-connect

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The method routing and middleware layer for Next.js (also works in micro or Node.js HTTP Server). Powered by trouter.

Installation

npm install next-connect
// or
yarn add next-connect

Usage

next-connect is often used in API Routes:

// pages/api/index.js
import nc from 'next-connect';

const handler = nc()
  .use(someMiddleware())
  .get((req, res) => {
    res.send('Hello world');
  })
  .post((req, res) => {
    res.json({ hello: 'world' });
  })
  .put(async (req, res) => {
    res.end('async/await is also supported!');
  })
  .patch(async (req, res) => {
    throw new Error('Throws me around! Error can be caught and handled.')
  });

export default handler;

For usage in pages with getServerSideProps, see .apply.

See an example in nextjs-mongodb-app (CRUD, Authentication with Passport, and more)

TypeScript

By default, the base interfaces of req and res are IncomingMessage and ServerResponse. When using in API Routes, you would set them to NextApiRequest and NextApiResponse by providing the generics to the factory function like so:

import { NextApiRequest, NextApiResponse } from 'next';
import nc from 'next-connect';

const handler = nc<NextApiRequest, NextApiResponse>()

In each handler, you can also define custom properties to req and res (such as req.user or res.cookie) like so:

interface ExtendedRequest { user: string };
interface ExtendedResponse { cookie: (name: string, value: string) => void };

handler.post<ExtendedRequest, ExtendedResponse>((req, res) => {
  req.user = 'Anakin';
  res.cookie('sid', '8108');
})

API

The API is similar to Express.js with several differences:

  • It does not include any helper methods or template engine (you can incorporate them using middleware)
  • It does not suppoprt error-handling middleware pattern. Use options.onError instead.

It is more like good ol' connect (hence the name) with method routing.

nc(options)

Initialize an instance of next-connect.

options.onError

Accepts a function as a catch-all error handler; executed whenever a middleware throws an error. By default, it responses with status code 500 and error message if any.

function onError(err, req, res, next) {
  logger.log(err);

  res.status(500).end(err.toString());
  // OR: you may want to continue
  next()
}

const handler = nc({ onError });

handler
  .use((req, res, next) => {
    throw new Error('oh no!');
    // or use next
    next(Error('oh no'));
  })
  .use((req, res) => {
    // this will run if next() is called in onError
    res.end('error no more');
  });

options.onNoMatch

Accepts a function of (req, res) as a handler when no route is matched. By default, it responses with 404 status and not found body.

function onNoMatch(req, res) {
  res.status(404).end('page is not found... or is it')
}

const handler = nc({ onNoMatch });

.use(base, ...fn)

base (optional) - match all route to the right of base or match all if omitted.

fn(s) are functions of (req, res[, next]) or an instance of next-connect, where it will act as a sub application.

// Mount a middleware function
handler.use((req, res, next) => {
  req.hello = 'world';
  // call next if you want to proceed to next in chain
  next();
});
// Or include a base
handler.use('/foo', fn); // Only run in /foo/**

// Mount an instance of next-connect
const common = nc().use(midd1).use(midd2); // You may have some common middleware to be used in every route.
const auth = nc().use('/dashboard', checkAuth);
const subapp = nc().get(getHandle).post('/baz', postHandle);
handler
  .use(common) // `midd1` and `midd2` runs everywhere
  .use(auth) // `checkAuth` runs on /dashboard/*
  .use('/foo', subapp); // `getHandle` runs on /foo while `postHandle` runs on /foo/baz

// You can use a library too.
handler.use(passport.initialize());

.METHOD(pattern, ...fns)

METHOD is a HTTP method (GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE) in lowercase.

pattern (optional) - match all route based on supported pattern or match all if omitted.

fn(s) are functions of (req, res[, next]). This is ideal to be used in API Routes.

handler.use('/user', passport.initialize());
handler.get('/user', (req, res, next) => {
  res.json(req.user);
});
handler.post('/users', (req, res, next) => {
  res.end('User created');
});
handler.put('/user/:id', (req, res, next) => {
  // https://nextjs.org/docs/routing/dynamic-routes
  res.end(`User ${req.query.id} updated`);
});
handler.get((req, res, next) => {
  res.end('This matches whatever route')
})

However, since Next.js already handles routing (including dynamic routes), we often omit pattern in .METHOD.

.apply(req, res)

Applies the middleware and returns a promise after which you can use the upgraded req and res.

This can be useful in getServerSideProps.

// page/index.js
export async function getServerSideProps({ req, res }) {
  const handler = nc()
    .use(passport.initialize())
    .post(postMiddleware);
  try {
    await handler.apply(req, res);
  } catch (e) {
    // handle the error
  }
  // do something with the upgraded req and res
  return {
    props: { user: req.user }
  };
}

Warning: .apply is not meant to be used as a request handler because it does not render 404 or onError accordingly.

Using in other frameworks

next-connect supports any frameworks that has the signature of (req, res).

Micro

const {send} = require('micro')
const handler = require('next-connect')()

handler
  .use(middleware)
  .get(() => 'hello world')
  .post((req, res) => {
    send(res, 200, { hello: 'world' })
  });

module.exports = handler;

Node.js HTTP Server

const http = require('http')
const handler = require('next-connect')()

handler
  .use(middleware)
  .get((req, res) => {
    res.end('Hello world');
  })
  .post((req, res) => {
    res.setHeader('content-type', 'application/json');
    res.end(JSON.stringify({ hello: 'world' }));
  });

http.createServer(handler).listen(PORT);

Contributing

Please see my contributing.md.

License

MIT

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