use mongoose and expressjs

Question

I want to develop an app using express.js and mongoose, to start an express server I need to write

var express = require('express');
var app = express();
var server = app.listen(3000, function () {});

and to connect to mongo, I need to write sth like this:

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');
var db = mongoose.connection;
db.once('open', function (callback) {
  // yay!
});

but I don't know how to combine these two codes, so that my server starts answering to request, only if my application has established a correct connection to mongo

Answer 1

create your app

var app = express();

create your db

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');
var db = mongoose.connection;

create connection handler with callback

var connectDB = function(next){
  //Bootstrap db connection
  mongoose.connect(db, function(err){
    if(err) return next(err);
    next();
  });
};

create your server

var server = http.createServer(app);
connectDB(function(err){
  var port = 8000;
  if(err) throw new Error('connection error');
  server.listen(port, function(){
    console.log('server listening on port ' + port);
  });
});