Express JS
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Express is a web framework for Node.js that allows routing, middleware, templating and more. It is inspired by Sinatra and uses Connect as its middleware framework. Key features include routing, middleware support, template rendering with engines like Jade, and session handling with storage options. Errors can be handled via the app.error() method. Express provides a full-featured and easy to use web development framework for Node.js.
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![HTTP POST
<form method="post" action="/">
<input type="text" name="user[name]" />
<input type="submit" value="Submit" />
</form>
bodyDecoder middleware for POST params:
app.use(express.bodyDecoder());
app.post('/', function(req, res){
console.log(req.body.user);
res.redirect('back');
});](https://image.slidesharecdn.com/expressjs-130408221102-phpapp02/85/Express-JS-7-320.jpg)
![HTTP PUT/DELETE
<form method="post" action="/">
<input type="hidden" name="_method" value="put" />
<input type="text" name="user[name]" />
<input type="submit" value="Submit" />
</form>
bodyDecoder and methodOverride:
app.use(express.bodyDecoder());
app.use(express.methodOverride());
app.post('/', function(req, res){
console.log(req.body.user);
res.redirect('back');
});](https://image.slidesharecdn.com/expressjs-130408221102-phpapp02/85/Express-JS-8-320.jpg)
Express JS
- 1. express high class web development for nodeJS Alok Guha
- 2. Whatâs express? ⢠nodeJS based web framework ⢠inspired by Sinatra ⢠asynchronous var app = express.createServer(); app.get('/', function(req, res){ res.send('Hello World'); }); app.listen(3000);
- 3. Installation ⢠Install nodeJS $ brew install node ⢠Install npm (node package manager) $ brew install npm ⢠Install express $ npm install express
- 4. Routing app.get('/users/:id?', function(req, res) { var id = req.params.id; res.send(id ? 'user ' + id : 'users'); }); app.post('/users/:id.:format', function(req, res) { var id = req.params.id; var format = req.params.format; res.send('user: ' + id + ' format: ' + format); }); app.get('/file/*.*', function(req, res) { res.send('path: ' + req.params); });
- 5. Connect / Middlewares ⢠Connect is a middleware framework ⢠Similar to Rack ⢠A middleware is simply a function with three arguments: request, response, next var helloWorld = function(req, res, next) { res.writeHead(200, { 'Content-Type': 'text/plain' }); res.end('hello world'); }
- 6. Middleware var loadUser = function(req, res, next) { var id = req.params.id; var user = db.loadUser(id); // fetch user from db if (user) { req.user = user; next(); } else { next(new Error('Failed to load user ' + id)); } } app.get('/user/:id', loadUser, function(req, res) { res.send('Viewing user ' + req.user.name); });
- 7. HTTP POST <form method="post" action="/"> <input type="text" name="user[name]" /> <input type="submit" value="Submit" /> </form> bodyDecoder middleware for POST params: app.use(express.bodyDecoder()); app.post('/', function(req, res){ console.log(req.body.user); res.redirect('back'); });
- 8. HTTP PUT/DELETE <form method="post" action="/"> <input type="hidden" name="_method" value="put" /> <input type="text" name="user[name]" /> <input type="submit" value="Submit" /> </form> bodyDecoder and methodOverride: app.use(express.bodyDecoder()); app.use(express.methodOverride()); app.post('/', function(req, res){ console.log(req.body.user); res.redirect('back'); });
- 9. View Rendering ⢠Concept: Layout, view and partials ⢠Template Engines: Jade, Haml, EJS, ⌠⢠View variables are passed to render app.set('view engine', 'jade'); app.get('/', function(req, res){ res.render('index.haml', { layout: 'app', // -> app.jade locals: { title: 'This is my app' } }); });
- 10. Jade - Template Engine !!! html(lang="en") head title= pageTitle :javascript | if (foo) | bar() body h1 Jade - node template engine #container - if (youAreUsingJade) p You are amazing - else p Get on it! .comments = partial('comment', comments)
- 11. Helpers app.dynamicHelpers({ flashes: function(req, res) { var msg = req.flash('message'); return msg.length ? '<p id="msg">' + msg + '</p>': ''; } }); app.helpers({ linkTo: function(text, url) { return '<a href=' + url + '>' + text + '</a>'; }, name: function(user) { return user.firstName + ' ' + user.lastName; } });
- 12. Sessions ⢠Currently depending on cookies ⢠Store implementations: Memory, Redis, ⌠app.use(express.cookieDecoder()); app.use(express.session()); app.post('/cart/add', function(req, res) { req.session.items = req.body.items; res.redirect('back'); }); app.get('/cart', function(req, res) { var items = req.session.items; res.render('cart', { locals: { items: items } }); });
- 13. Error Handling The app.error() method receives exceptions thrown within a route, or passed to next(err) app.use(express.errorHandler({ dumpExceptions: true })); app.error(function(err, req, res, next) { if (err instanceof Unauthorized) { res.render('401.jade', { locals: { error: err } }); } else if (err instanceof NotFound) { res.render('404.jade'); } else { next(err); } });
- 14. Why express? ⢠Full-blown feature set ⢠Built on Connect ⢠Good documentation ⢠Lots of examples ⢠Many extensions ⢠Nice community
- 15. Going further⌠⢠http://expressjs.com/guide.html ⢠http://expressjs.com/api.html ⢠http://senchalabs.github.com/connect/ ⢠http://github.com/senchalabs/connect/wiki ⢠http://github.com/visionmedia/express/tree/ master/examples/ ⢠https://github.com/dbloete/Codeshelver