Building your first Node app with Connect & Express

Building your first Node app with Connect & Express Christian Joudrey - @cjoudrey

Getting Started Node.js: http://nodejs.org/#download npm, a package manager for Node: curl http://npmjs.org/install.sh | sh Use npm to install Connect and Express for Node: npm install connect && npm install express Many more modules at: http://npm.mape.me/

Hello World in Node.js // Load the http module var http = require(' http '); // Setup a HTTP server, listen on port 8080 http.createServer(function (req, res) { res.writeHead(200, { ' Content-Type ': ' text/plain ' }); res.end(' Hello World '); }).listen(8080, ' 127.0.0.1 ');

Node's HTTP module Very low level. No cookie handling or parsing. No session support built-in. No routing built-in. No static file serving.

Connect makes it easier Static File Server Body Decoder Cookie Decoder Session Provider Request Router Logs Sass/Less Compiler Virtual Host Router

...but, you decide what blocks you want.

Hello World in Connect // Load the connect module var connect = require(' connect '); // Setup a HTTP server, listen on port 8080 connect.createServer(function (req, res) { res.writeHead(200, { ' Content-Type ': ' text/plain ' }); res.end(' Hello World '); }).listen(8080, ' 127.0.0.1 ');

.use() and next() var connect = require(' connect '); var s = connect.createServer(); s.use(function (req, res, next) { // Send to next handler if url not /about if (req.url != ' /about ') return next(); res.end(' About page '); }); s.use(function (req, res, next) { res.end(' Default page '); }); s.listen(8080, ' 127.0.0.1 ');

Routing Middleware s.use(connect.router(function(app) { app.get(' /users ', function(req, res, next) { res.end(' List users '); }); app.post(' /users ', function(req, res, next) { res.end(' Create a new user '); }); app.get(' /user/:id ', function(req, res, next) { if (!is_admin(req)) { return next( new Error(' access denied ')); } res.end(' Edit user ' + req.params.id); }); })); s.use(function(err, req, res, next) { res.end(err.message); });

Full example with Connect var connect = require(' connect '); var s = connect.createServer(); s.use(connect.logger()); s.use(connect.favicon(__dirname + ' /static/favicon.ico ')); s.use(connect.static(__dirname + ' /static ')); s.use(connect.cookieParser()); // adds req.cookies s.use(connect.bodyParser()); // adds req.body s.use(connect.router(require(' ./users ')); s.use(connect.router(require(' ./index ')); s.use(function(err, req, res, next) { res.end(' Internal Server Error '); }); s.listen(8080, ' 127.0.0.1 ');

Express is even easier Connect is easier than raw node.js, but still low level. ...but, it's good for simple RESTful API's ...or to make your own framework. Express is a simple framework inspired by Sinatra (Ruby). It's built on top of Connect.

Hello World in Express var express = require(' express '); var app = express.createServer(); app.get(' / ', function(req, res) { res.send(' hello world '); }); app.listen(8080);

Getting Started with Express Generate skeleton apps: express –help Generate app with sessions and template engine: express --sessions --template ejs hello Generated structure: $ ls hello/ app.js logs pids public test views $ ls hello/views/ index.ejs layout.ejs

Configurations app.configure(function() { // Global configurations app.use(express.bodyParser()); // parse incoming data app.use(express.cookieParser()); // parse cookies app.use(express.session({ secret: ' your secret ' }); }); app.configure(' development ', function() { // Development configurations // i.e. Error handler to print errors and show stack? }); app.configure(' production ', function() { // Production configurations }); Controlled by: NODE_ENV=production node app.js

Routing app.get(' /users ', function(req, res) { // List user }); app.post(' /users ', function(req, res) { // Create user // req.body contains POST data }); app.get(' /user/:id ', function(req, res) { // Edit user // req.params.id contains value of :id param });

Sanitizing Route Params app.param(' :id ', function(v) { return parseInt(v, 10); }); app.get(' /user/:id ', function(req, res) { res.send(' user id: ' + req.params.id); });

Even better... var integer = function(v) { return parseInt(v, 10); }; app.param(' :id ', integer); app.get(' /user/:id ', function(req, res) { res.send(' user id: ' + req.params.id); });

Route Param Pre-conditions app.get(' /user/:id ', function(req, res) { var id = req.params.id; User.get(id, function(err, user) { if (err) return next(err); res.send(' user ' + user.name); }); }); app.put(' /user/:id ', function(req, res) { var id = req.params.userId; User.get(id, function(err, user) { if (err) return next(err); user.update(req.body); }); }); Same logic every time there is :id

Even better... var loadUser = function(req, res, next) { var id = req.params.id; User.get(id, function(err, user) { if (err) return next(err); if (!user) return next( new Error(' invalid userId ')); req.user = user; next(); }); }); app.get(' /user/:id ', loadUser, function(req, res) { res.send(' user ' + req.user.name); }); app.put(' /user/:id ', loadUser, function(req, res) { req.user.update(req.body); });

You can stack them... app.put(' /user/:id ', isAdmin, loadUser, function(req, res) { req.user.update(req.body); }); app.put(' /user/:id ', function(req, res, next) { // Verify if the current user is an admin isAdmin(req, res, function(err) { if (err) return next(err); loadUser(req, res, function(err, user) { if (err) return next(err); req.user.update(req.body); }); }); }); ...cleaner than...

Views "Built-in" support for : Jade (Haml-like): http://jade-lang.com/ EJS (Embedded JS): http://embeddedjs.com/ Support for partials.

Rendering Views app.get(' /user/:id ', loadUser, function(req, res) { res.render(' user_edit ', { locals: { user: req.user, title: ' Edit User ' + req.user.username } }); });

Other useful functions... app.helpers(Object) Set functions that are available in your views app.dynamicHelpers(Object) Set helpers that require the req and res objects app.error(Function), called when: throw new Error() next(new Error())

Interesting Links Lots of Express examples: http://bit.ly/ExpressExamples Express Documentation: http://bit.ly/ExpressDocs Database wrappers and ORMs: Mongoose (MongoDB, ORM-like): https://github.com/LearnBoost/mongoose Cradle (CouchDB, HTTP wrapper): https://github.com/cloudhead/cradle Couch-ar (CouchDB, Active Record implementation): https://github.com/scottburch/couch-ar

Building your first Node app with Connect & Express

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