Rest with Express.js nested router

Question

Suppose I want to have REST endpoints which look roughly like this:

/user/
/user/user_id 

/user/user_id/items/
/user/user_id/items/item_id

CRUD on each if makes sense. For example, /user POST creates a new user, GET fetches all users. /user/user_id GET fetches just that one user.

Items are user specific so I put them under user_id, which is a particular user.

Now to make Express routing modular I made a few router instances. There is a router for user, and a router for the item.

var userRouter = require('express').Router();
userRouter.route('/')
  .get(function() {})
  .post(function() {})
userRouter.route('/:user_id')
  .get(function() {})

var itemRouter = require('express').Router();
itemRouter.route('/')
  .get(function() {})
  .post(function() {})
itemRouter.route('/:item_id')
  .get(function() {})

app.use('/users', userRouter);

// Now how to add the next router?
// app.use('/users/', itemRouter);

URL to item is descendents of the URL hierarchy of the user. Now how do I get URL with /users whatever to userRouter but the more specific route of /user/*user_id*/items/ to the itemRouter? And also, I would like user_id to be accessible to itemRouter as well, if possible.

Answer 1

You can nest routers by attaching them as middleware on an other router, with or without params.

You must pass {mergeParams: true} to the child router if you want to access the params from the parent router.

mergeParams was introduced in Express 4.5.0 (Jul 5 2014)

In this example the itemRouter gets attached to the userRouter on the /:userId/items route

This will result in following possible routes:

GET /user -> hello user
GET /user/5 -> hello user 5
GET /user/5/items -> hello items from user 5
GET /user/5/items/6 -> hello item 6 from user 5

var express = require('express');
var app = express();

var userRouter = express.Router();
// you need to set mergeParams: true on the router,
// if you want to access params from the parent router
var itemRouter = express.Router({mergeParams: true});

// you can nest routers by attaching them as middleware:
userRouter.use('/:userId/items', itemRouter);

userRouter.route('/')
    .get(function (req, res) {
        res.status(200)
            .send('hello users');
    });

userRouter.route('/:userId')
    .get(function (req, res) {
        res.status(200)
            .send('hello user ' + req.params.userId);
    });

itemRouter.route('/')
    .get(function (req, res) {
        res.status(200)
            .send('hello items from user ' + req.params.userId);
    });

itemRouter.route('/:itemId')
    .get(function (req, res) {
        res.status(200)
            .send('hello item ' + req.params.itemId + ' from user ' + req.params.userId);
    });

app.use('/user', userRouter);

app.listen(3003);

Answer 2

manageable nested routes...

I wanted a specific example of doing nested routes in a very manageable way in express 4 and this was the top search result for "nested routes in express". Here's an API that would have many routes that would need to be broken up for example.

./index.js:

var app = require('express')();

// anything beginning with "/api" will go into this
app.use('/api', require('./routes/api'));

app.listen(3000);

./routes/api/index.js:

var router = require('express').Router();

// split up route handling
router.use('/products', require('./products'));
router.use('/categories', require('./categories'));
// etc.

module.exports = router;

./routes/api/products.js:

var router = require('express').Router();

// api/products
router.get('/', function(req, res) {
  res.json({ products: [] });
});

// api/products/:id
router.get('/:id', function(req, res) {
  res.json({ id: req.params.id });
});

module.exports = router;

Nesting example in folder structure

I noticed some comments on "nesting folder structure". It is implied in this however not obvious so I added the section below. Here's a specific example of a nested folder structure for routes.

index.js
/api
  index.js
  /admin
    index.js
    /users
      index.js
      list.js
    /permissions
      index.js
      list.js

This is more a general example of how node works. If you use "index.js" in folders similarly to how "index.html" works in web pages for a directory default, this will be easy to scale your organization based off of recursion without changing your entry points to code. "index.js" is the default document accessed when using require in a directory.

contents of index.js

const express = require('express');
const router = express.Router();
router.use('/api', require('./api'));
module.exports = router;

contents of /api/index.js

const express = require('express');
const router = express.Router();
router.use('/admin', require('./admin'));
module.exports = router;

contents of /api/admin/index.js

const express = require('express');
const router = express.Router();
router.use('/users', require('./users'));
router.use('/permissions', require('./permissions'));
module.exports = router;

contents of /api/admin/users/index.js

const express = require('express');
const router = express.Router();
router.get('/', require('./list'));
module.exports = router;

There is some DRY issues here possibly but it does lend itself well to encapsulation of concerns.

FYI, recently I got into actionhero and have found it to be full featured w/sockets and tasks, more like a true framework all-in-one flipping the REST paradigm on its head. You should probably check it out over going naked w/ express.

Answer 3

var userRouter = require('express').Router();
var itemRouter = require('express').Router({ mergeParams: true }); 

userRouter.route('/')
  .get(function(req, res) {})
  .post(function(req, res) {})
userRouter.route('/:user_id')
  .get(function() {})

itemRouter.route('/')
  .get(function(req, res) {})
  .post(function(req, res) {})
itemRouter.route('/:item_id')
  .get(function(req, res) {
    return res.send(req.params);
  });

app.use('/user/', userRouter);
app.use('/user/:user_id/item', itemRouter);

The key to the second part of your question is the use of the mergeParams option

var itemRouter = require('express').Router({ mergeParams: true }); 

From /user/jordan/item/cat I get a reponse:

{"user_id":"jordan","item_id":"cat"}

Answer 4

In the spirit of Express modular routers, we should have a separate router for users and for items. That router isn't part of our top-level application logic. We can nest it in our users' router instead.

Users router

const users = require('express').Router();
const items = require('./items');

//...

// Our root route to /users
albums.get('/', function(req, res, next) {
  // res.send() our response here
});

// A route to handle requests to any individual user, identified by an user id
users.get('/:userId', function(req, res, next) {
  let userId = req.params.userId;
  // retrieve user from database using userId
  // res.send() response with user data
});

// Note, this route represents /users/:userId/items because our top-level router is already forwarding /users to our Users router!
users.use('/:userId/items', items);

//...

module.exports = users;

Items router

// We need to merge params to make userId available in our Items router
const items = require('express').Router({ mergeParams: true });

//...

// The root router for requests to our items path
items.get('/', function(req, res, next) {
  let userId = req.params.userId; // Here is where mergeParams makes its magic

  // retrieve user's track data and render items list page
});

// The route for handling a request to a specific item
items.get('/:itemId', function(req, res, next) {
  let userId = req.params.userId; // <-- mergeParams magic
  let itemId = req.params.itemId;

  // retrieve individual item data and render on single item page
});

//...

module.exports = items;

Source

Answer 5

Using @Jason Sebring solution, and adapting for Typescript.

server.ts

import Routes from './api/routes';
app.use('/api/', Routes);

/api/routes/index.ts

import { Router } from 'express';
import HomeRoutes from './home';

const router = Router();

router.use('/', HomeRoutes);
// add other routes...

export default router;

/api/routes/home.ts

import { Request, Response, Router } from 'express';

const router = Router();

router.get('/', (req: Request, res: Response) => {
  res.json({
    message: 'Welcome to API',
  });
});

export default router;

Answer 6

try to add { mergeParams: true } look to simple example which it middleware use it in controller file getUser at the same for postUser

const userRouter = require("express").Router({ mergeParams: true });
export default ()=>{
  userRouter
    .route("/")
    .get(getUser)
    .post(postUser);

  userRouter.route("/:user_id").get(function () {});
}

Answer 7

Express router(express.Router()) keeps params seprate so you would explicitly have to tell express to merge these params. eg: express.Router({ mergeParams: true })

//above line is answer to your question.

Answer 8

You need only one router, and use it like this:

router.get('/users');
router.get('/users/:user_id');

router.get('/users/:user_id/items');
router.get('/users/:user_id/items/:item_id');

app.use('api/v1', router);