using object in another js file

Question

I am getting my hands on node.js and I am trying to understand the whole require/exports thing. I have the following main app.js file:

/app.js

var express  = require('express'),
    http     = require('http'),
    redis    = require('redis'),
    routes   = require('./routes'),

var app    = express(),
    client = redis.createClient();


// some more stuff here...
// and my routes

app.get('/', routes.index);

then, I have the routes file:

exports.index = function(req, res){
  res.render('index', { title: 'Express' });
};

I can of course use the client object on my app.js file, but how can I use the same object in my routes?

Jonathan Lonowski · Accepted Answer · 2013-08-18 21:31:28Z

1

Since req and res are already being passed around by Express, you can attach client to one or both in a custom middleware:

app.use(function (req, res, next) {
  req.client = res.client = client;
  next();
});

Note that order does matter with middleware, so this will need to be before app.use(app.router);.

But, then you can access the client within any route handlers:

exports.index = function(req, res){
  req.client.get(..., function (err, ...) {
    res.render('index', { title: 'Express' });
  });
};

edited Aug 18, 2013 at 21:31

answered Aug 18, 2013 at 21:24

Jonathan Lonowski

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3 Comments

john smith Over a year ago

can I pass it in another object instead of attaching it to req or res?

Jonathan Lonowski Over a year ago

@johnsmith Not really. Express isn't passing any other objects, so including one requires closures, which is what Problematic suggested. Attaching to req and res is a rather common practice and is how most Connect middleware work (Express being an extension of Connect). You can also find a real-world example of this type of attachment in the npm-www project, the source behind npmjs.org.

john smith Over a year ago

that's pretty cool, thank you! I think iI'll stick with this as it seems a more elegant solution to me

Problematic · Accepted Answer · 2013-08-18 20:55:55Z

1

The easiest way is to export a function from your routes file that takes a client, and returns an object with your routes:

exports = module.exports = function (client) {
    return {
        index: function (req, res) {
            // use client here, as needed
            res.render('index', { title: 'Express' });
        }
    };
};

Then from app.js:

var client = redis.createClient(),
    routes = require('./routes')(client);

answered Aug 18, 2013 at 20:55

Problematic

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1 Comment

john smith Over a year ago

is that the only way to do it? I'm not an expert at all so I have no idea what I am saying but that surely looks kind of complicated! :D

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