next-connect

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 nextConnect from "next-connect";

const handler = nextConnect();

handler
  .use(someMiddleware())
  .get((req, res) => {
    res.send("Hello world");
  })
  .post((req, res) => {
    res.json({ hello: 'world' });
  });

export default handler;

For usage in pages with getServerSideProps, see .apply.

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

API

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

nextConnect(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 = nextConnect({ 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 = nextConnect({ 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.

handler.use((req, res, next) => {
  req.hello = 'world';
  // call next if you want to proceed to next in chain
  next();
});

// Reuse an instance of nextConnect
const anotherHandler = nextConnect()
anotherHandler.use(commonFn).use(anotherFn);
handler.use(anotherHandler);

// 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 matchs 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 = nextConnect();
  handler.use(passport.initialize());
  try {
    await handler.apply(req, res);
  } catch(e) {
    // handle the error
  }
  // do something with the upgraded req and res
  return {
    props: { user: req.user }, // will be passed to the page component as props
  }
};

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

module.exports = handler;

Node.js HTTP Server

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

handler
  .use(someMiddleware())
  .get((req, res) => {
    res.send("Hello world");
  })
  .post((req, res) => {
    res.json({ hello: 'world' });
  });

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

Contributing

Please see my contributing.md.

License

MIT