Grapnel Server-Side Router Framework for Node.js

Simple JavaScript Router for Node.js with Named Parameters and Middleware support.

Download/Installation

Install with npm

npm install grapnel-server

Grapnel Features

• Supports Named Parameters similar to Sinatra, Restify, and Express
• Middleware Support
• RegExp Support
• No dependencies

Server-Side Routing

var http = require('http'),
    app = require('grapnel-server');

app.get('/products/:category/:id?', function(req, res, next){
    var id = req.params.id,
        category = req.params.category

    console.log(category, id);

    res.end('Hello World!', 200);
});

http.createServer(app.start()).listen(3000);

Named Parameters

Grapnel.js supports regex style routes similar to Sinatra, Restify, and Express. The properties are mapped to the parameters in the request.

app.get('products/:id?', function(req, res){
    // GET /products/134
    req.params.id
    // => 134
});

app.get('products/*', function(req, res){
    // The wildcard/asterisk will match anything after that point in the URL
    // Parameters are provided req.params using req.params[n], where n is the nth capture
});

Middleware Support

Grapnel.js also supports middleware:

var auth = function(req, res, next){
    user.auth(function(err){
        req.user = this;
        next();
    });
}

app.get('/*', auth, function(req, res){
    console.log(req.user);
    res.end('Hello ' + req.user.name, 200);
});

Route Context

You can add context to a route and even use it with middleware:

var usersRoute = router.context('/user/:id', getUser, getFollowers); // Middleware can be used here

usersRoute.get('/', function(req, res, next){
    console.log('Profile', req.params.id);
});

usersRoute.get('/followers', otherMiddleware, function(req, res, next){ // Middleware can be used here too
    console.log('Followers', req.params.id);
});

usersRoute.post('/', function(req, res, next){ // Middleware can be used here too
    console.log('POSTED to /user/:id', req.params.id);
});

// GET /user/13589
// => Profile 13589

// GET /user/13589/followers
// => Followers 13589

// POST /user/13589
// => POSTED to 13589

Declaring Multiple Routes

var Grapnel = require('grapnel-server').Server;

var routes = {
    'products' : function(req, res, next){
        // GET /products
    },
    'products/:category/:id?' : function(req, res, next){
        // GET /products/widgets/35
        req.params.category
        // => widgets
    }
}

Grapnel.listen(routes);

Event Handling

var app = require('grapnel-server');

app.on('navigate', function(){
    // GET /foo/bar
    console.log('URL changed to %s', this.path());
    // => URL changed to /foo/bar
});

RegExp Support

Grapnel.js allows RegEx when defining a route:

var expression = /^\/food\/tacos\/(.*)$/i;

app.get(expression, function(req, res){
    // GET /food/tacos/good
    console.log('I think tacos are %s.', req.params[0]);
    // => "He thinks tacos are good."
});

Usage & Tips

Middleware

Grapnel uses middleware similar to how Express uses middleware. Middleware has access to the req object, event object, and the next middleware in the call stack (commonly denoted as next). Middleware must call next() to pass control to the next middleware, otherwise the router will stop.

For more information about how middleware works, see Using Middleware.

var user = function(req, res, next){
    user.get(function(err){
        req.user = this;
        next();
    });
}

app.get('/user/*', user, function(req, res){
    console.log(req.user);
    res.send(req.user.name);
});

Stopping a Route Event

app.on('match', function(req){
    req.event.preventDefault(); // Stops event handler
});

Stopping Event Propagation

app.get('/products/:id', function(req, res){
    req.event.stopPropagation(); // Stops propagation of the event
});

app.get('/products/widgets', function(req, res){
    // This will not be executed
});

// GET /products/35

404 Pages

You can specify a route that only uses a wildcard * as your final route, then use req.event.parent() which returns false if the call stack didn't run any route handlers.

// This should be your last route
app.all('*', function(req, res){
    if(!this.state.parent()){
        res.writeHead(404);
        res.end('404');
    }
});

API Documentation

get, post, put, delete (HTTP Method) Adds a listeners and middleware for routes matching its respective HTTP method

/**
 * @param {String|RegExp} path
 * @param {Function} [[middleware], callback]
*/
app.get('/store/:category/:id?', function(req, res){
    var category = req.params.category,
        id = req.params.id;

    console.log('Product #%s in %s', id, category);
});

app.post('/store/:category', function(req, res){
    var category = req.params.category;

    console.log('POST Product %s', category);
});

app.put('/store/:category', function(req, res){
    var category = req.params.category,
        id = req.params.id;

    console.log('PUT Product #%s in %s', id, category);
});

app.delete('/store/:category/:id', function(req, res){
    var category = req.params.category,
        id = req.params.id;

    console.log('DELETE Product #%s in %s', id, category);
});

app.all('/store/', function(req, res){
    // This will be called with any HTTP method
});

on Adds a new event listener

/**
 * @param {String} event name (multiple events can be called when separated by a space " ")
 * @param {Function} callback
*/
router.on('myevent', function(event){
    console.log('Grapnel.js works!');
});

once A version of on except its handler will only be called once

/**
 * @param {String} event name (multiple events can be called when separated by a space " ")
 * @param {Function} callback
*/
router.once('init', function(){
    console.log('This will only be executed once');
});

trigger Triggers an event

/**
 * @param {String} event name
 * @param {Mixed} [attributes] Parameters that will be applied to event handler
*/
app.trigger('event', eventArg1, eventArg2, etc);

context Returns a function that can be called with a specific route in context.

Both the router.context method and the function it returns can accept middleware. Additionally, you can specify which HTTP method (GET, POST, PUT, DELETE) should be routed by the callback. Not specifying an HTTP method will assume GET.

Note: when calling route.context, you should omit the trailing slash.

/**
 * @param {String} Route context (without trailing slash)
 * @param {[Function]} Middleware (optional)
 * @return {Function} Adds route to context
*/
var usersRoute = router.context('/user/:id');

usersRoute.post('/', function(req, res, next){
    console.log('POSTED to', req.params.id);
});

// Not specifying an HTTP method assumes GET
usersRoute('/followers', function(req, res, next){
    console.log('Followers', req.params.id);
});

// GET /user/13589/followers
// => Followers 13589

// POST /user/13589
// => Followers 13589

bind An alias of on

add An alias of get

path

• router.path('string') Sets a new path or hash
• router.path() Gets path or hash
• router.path(false) Clears the path or hash

fragment (Deprecated)

Events

• navigate Fires when http module initializes a new request
• match Fires when a new match is found, but before the handler is called

License

MIT License