Hierarchical routing with plain Express.js

Question

I’m implementing a RESTful API using Node and Express. When it comes to routing, currently it looks like this:

var cat = new CatModel();
var dog = new DogModel();

app.route('/cats').get(cat.index);
app.route('/cats/:id').get(cat.show).post(cat.new).put(cat.update);

app.route('/dogs').get(dog.index);
app.route('/dogs/:id').get(dog.show).post(dog.new).put(dog.update);

I don’t like this for two reasons:

1. Both cat and dog models are instantiated whether I need them or not.
2. I have to repeat /cats and /dogs for every path schema

I’d love to have something like this (not working, of course):

app.route('/cats', function(req, res)
{
    var cat = new CatModel();

    this.route('/').get(cat.index);
    this.route('/:id').get(cat.show).post(cat.new).put(cat.update);
});

app.route('/dogs', function(req, res)
{
    var dog = new DogModel();

    this.route('/').get(dog.index);
    this.route('/:id').get(dog.show).post(dog.new).put(dog.update);
});

Is there a clean way in modern Express without any further modules (like express-namespace)? I could go for separate routers for each model and assigning them with app.use('/cats', catRouter). However, what if I have more than one hierarchy level like '/tools/hammers/:id'? I would then have routers within routers within routers, which seems like overkill to me.

Answer 1

I would then have routers within routers within routers, which seems like overkill to me.

Perhaps, but that is the built-in method of prefixing -- to app.use() a Router().

var cats = express.Router();
app.use('/cats', cats);

cats.route('/').get(cat.index);
cats.route('/:id').get(cat.show).post(cat.new).put(cat.update);

// ...

And, to have one Router .use() another to define multiple depths:

var tools = express.Router();
app.use('/tools', tools);

var hammers = express.Router();
tools.use('/hammers', hammers);

// effectively: '/tools/hammers/:id'
hammers.route('/:id').get(...);

---

Though, to be closer to your 2nd snippet, you can define a custom method:

var express = require('express');

express.application.prefix = express.Router.prefix = function (path, configure) {
    var router = express.Router();
    this.use(path, router);
    configure(router);
    return router;
};

var app = express();

app.prefix('/cats', function (cats) {
    cats.route('/').get(cat.index);
    cats.route('/:id').get(cat.show).post(cat.new).put(cat.update);
});

app.prefix('/dogs', ...);

app.prefix('/tools', function (tools) {
    tools.prefix('/hammers', function (hammers) {
        hammers.route('/:id').get(...);
    });
});

Answer 2

Check out the new Router in Express 4. It sounds exactly what you're looking for.