Passing database connection around in a nodejs application

Question

I'm using express 3 in my node application and I've broken my routes into separate files...

app.use('/', routes);
app.use('/users', users);

The problem is that I need a database connection in many of these routes. Should I be connecting to the database in each of the route files or can I connect in my main app file and somehow pass the connection to the includes?

---

I used express-generator to create a skeleton app. In app.js the routes are included like this...

app.use('/', routes);
app.use('/users', users);

And in each other these files there are routes as follows...

var express = require('express');
var router = express.Router();

router.get('/', function(req, res) {
    res.render('index');
});

Answer 1

I simply keep the database connection in the app:

app.set('db',new MyDAO(config)); <-- use where you define your routes.

then, inside the route, in get() or post() I simply do

req.app.get('db').usercollection.find()

This way you keep your database connection pool attached to the gloabl application context.

Alternative common approach is to extend req on every request, but it is executed every time:

app.use(function(req,res,next){
    req.db = db; //this db comes from app.js context where you define it
    next();
});