How to delegate route processing in express?

Question

I have expressjs application with straitfort route processing like the following:

app.route('/').get(function(req, res, next) {
   // handling code;
});

app.route('/account').get(function(req, res, next) {
   // handling code;    
});

app.route('/profile').get(function(req, res, next) {
   // handling code;
});

At now I put all my code inside route handler but I want try to delegate it to some class such as the following.

app.route('/').get(function(req, res, next) {
   new IndexPageController().get(req, res, next);
});

app.route('/account').get(function(req, res, next) {
   new AccountPageController().get(req, res, next);
});

app.route('/profile').get(function(req, res, next) {
   new ProfilePageController().get(req, res, next);
});

So what do you thing about the approach above and meybe you know the better one?

Andrey Popov · Accepted Answer · 2015-11-27T23:41:50.753

As you can see in the Express Response documentation - the response (req) can send information to the client by a few methods. The easiest way is to use req.render like:

// send the rendered view to the client
res.render('index');

Knowing this means that you can do whatever you want in another function, and at the end just call res.render (or any other method that sends information to the client). For example:

app.route('/').get(function(req, res, next) {
   ndexPageController().get(req, res, next);
});

// in your IndexPageController:

function IndexPageController() {
    function get(req, res, next) {
        doSomeDatabaseCall(function(results) {
            res.render('page', results);
        }
    }

    return {
        get: get
    }
}
// actually instantiate it here and so module.exports
// will be equal to { get: get } with a reference to the real get method
// this way each time you require('IndexPageController') you won't
// create new instance, but rather user the already created one
// and just call a method on it.
module.exports = new IndexPageController();

There isn't strict approach to this. You can pass the response and someone else call render. Or you can wait for another thing to happen (like db call) and then call render. Everything is up to you - you just need to somehow send information to the client :)

thanks for the response. I'm just woried about creating new object each time for each request. — Erik, Nov 27 '15 at 16:27
Then create singleton files (with a single instance). This way you will have one instance and call it's method for each request. Just updated my answer. — Andrey Popov, Nov 27 '15 at 23:39
Thanks for the response but I want create new instance of controller on every request. Does it impact to performance or memory increasing? — Erik, Nov 30 '15 at 06:57
"I'm just woried about creating new object each time for each request.", "I want create new instance of controller on every request". Well buddy, everything depends on you :) Of course there is an impact, but it all depends on your code. I don't see any idea creating new controller, as long as you can call different function.. — Andrey Popov, Nov 30 '15 at 07:13

How to delegate route processing in express?

1 Answers1