switchyard

Dynamic routing library for express.js

The Problem

express.js makes development of RESTful applications a cinch. Unfortunately, it makes ugly application organization a cinch as well. How often have you seen single-page express.js applications that end up as route soup?

// bad-application.js
app.get( '/endpoint', function() { ... } );
app.post( '/endpoint', function() { ... } );
app.get( '/another-endpoint', function() { ... } );
app.patch( '/some-endpoint/:id', function() { ... } );

As applications grow, they sometimes become more organized. The tight coupling between routes and controllers remains, however; to locate the function that defines a route, you'll need to search the entire codebase.

Enter switchyard. switchyard performs dynamic routing based on controller structure. Your code now defines its routes implicitly, and simple separation of controllers is simple.

Installation

To install switchyard, just require it from npm:

npm install --save switchyard

Usage

Using switchyard is simple. Place your controllers in one director (we'll use controllers for our examples). A simple example server:

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

// Starting switchyard is simple. Pass your express.js instance as the first
// parameter, and the full path to your controller directory as the second.
switchyard( app, __dirname + '/controllers' );

var server = app.listen( 3000, function() {
    console.log( 'A switchyard-powered express server is running on port 3000!' );
} );

Controller Syntax

Controllers are placed in your defined controller directory (the second parameter to switchyard). Their URL routes are generated by their name; for example, to create a controller that responds to endpoints beginning with /user, name your controller user.js. Controllers expose a single object that defines their behavior.

// controllers/user.js
module.exports = {
    // Endpoints that respond to /user/hello
    hello: {
        // GET /user/hello
        get: function( req, res ) {
            res.send( 'Hello, world!' );
        }
    }
};

These objects are two dimensional. The first dimension is the endpoint name (which will be reflected directly in the URL, as the comments above indicate). The second dimension controls the response to each HTTP verb, and returns a function that maps directly to an express.js route that defines the behavior. Every HTTP verb that express supports is supported here: GET, POST, PATCH, PUT, DELETE, etc.

Special endpoint names

If you'd like to map directly to the / route for a controller (for example, /user/), you can used the index route.

// controllers/test.js
module.exports = {
    // Endpoints that respond to /test/
    index: {
        // POST /test
        post: function( req, res ) {
            // ... do something
        }
    }
};

You can also use named routes, e.g. /user/view/:id.

// controllers/user.js
module.exports = {
    "view/:id": {
        get: function( req, res ) {
            var user_id = req.param( 'id' );
            res.send( 'Hello, user ' + user_id + '!' );
        }
    }
};

Route aliases

You can also define special routes, which don't match the controller name/method convention. To do this, pass a third parameter to the switchyard instantiation:

var route_aliases = {
    '/login': '/user/login',
    '/logout': '/user/logout'
};

switchyard( app, __dirname + '/controllers', route_aliases );

The key in the route_alias object is the alias URL you'd like to define, and the value is the path that it will map to. In this example, /login will now map to the login endpoint in controllers/user.js.

Aliases automatically map to every verb on the endpoint: for example, if controllers/user.js:login defined a GET and POST method, so would /login.

Multiple aliases may point to the same controller.

Coming Soon

I have a few future things I'd like to support that are coming soon:

• Subdirectories in the controller directory

Contributing

Pull requests are gladly appreciated! You are also free to create issues for feature requests, bugs, or to complain about this documentation.