Express Routers and Middleware

Separating Routes

Having all of the routes and controllers in a single file can be difficult to maintain.

Express allows the separation of server routes into smaller sub routers.

An app.js file with the following routes set-up can be refactored to use multiple express routers:

// app.js
app.get('/api/users', (req, res) => {
  res.status(200).send('All OK from /api/users');
});
 
app.get('/api/users/:id', (req, res) => {
  res.status(200).send('All OK from /api/users/:id');
});
 
app.get('/api/users/:id/shoppingList', (req, res) => {
  res.status(200).send('All OK from /api/users/:id/shoppingList');
});
 
app.get('/api/fruits', (req, res) => {
  res.status(200).send('All OK from /api/fruits');
});
 
app.get('/api/fruits/:id', (req, res) => {
  res.status(200).send('All OK from /api/fruits/:id');
});

Project structure (excluding models and controllers):

  express-routing-example/
└────     node_modules/
└────     routes/
│  ├────     api-router.js
│  ├────     fruits-router.js
│  └────     users-router.js
├────     app.js
├────     listen.js
├────     package-lock.json
└────     package.json

// api-router.js
const apiRouter = require('express').Router();
 
apiRouter.get('/', (req, res) => {
  res.status(200).send('All OK from API Router');
});
 
module.exports = apiRouter;

We can refactor app.js to use the apiRouter on all routes beginning with "/api":

// app.js
const apiRouter = require('./routes/api');
 
app.use('/api', apiRouter);
// ...

Express allows multiple sub-routers. This is a separate userRouter that can funnel all our user requests:

// users-router.js
const userRouter = require('express').Router();
 
userRouter.get('/', (req, res) => {
  res.status(200).send('All OK from /api/users');
});
 
userRouter.get('/:id', (req, res) => {
  res.status(200).send('All OK from /api/users/:id');
});
 
userRouter.get('/:id/shoppingList', (req, res) => {
  res.status(200).send('All OK from /api/users/:id/shoppingList');
});
 
module.exports = userRouter;

apiRouter can then be refactored to use the userRouter.

// api-router.js
const apiRouter = require('express').Router();
const userRouter = require('./users');
 
apiRouter.use('/users', userRouter);
 
module.exports = apiRouter;

The same can be done for the /fruits endpoints to segment each route depending on the resource that the user is requesting.

The benefit of this it to keep code tidy and easier to maintain and manage.

router.route()

Routes can be organised further when a particular route accepts different types of HTTP methods by using .route().

// users-router.js
userRouter
  .route('/')
  .get((req, res) => {
    res.status(200).send('All OK from GET /api/users');
  })
  .post((req, res) => {
    res.status(200).send('All OK from POST /api/users');
  })
  .patch((req, res) => {
    res.status(200).send('All OK from PATCH /api/users');
  });
 
userRouter
  .route('/:id')
  .get((req, res) => {
    res.status(200).send('All OK from GET /api/users/:id');
  })
  .patch((req, res) => {
    res.status(200).send('All OK from PATCH /api/users/:id');
  });
// ...

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