node.js - Why mongoose.model.create's Callback Isn't Executed from within Express 3.x HTTP Request Handler (connect-mongodb is the cause, actually) -

to put problem stright in code:

expressapp.get('/', function requesthandler(req, res) {   usermongoosemodel.create(userpropertiesdict, never_called_callback);   console.log('this printed fine browser awaits response forever.'); } 

express 3.x, mongoose 3.x.
imprtant details of initialization:

mongoose.connect(mongourl); var mongostore = require('connect-mongodb'); // not 'connect-mongo', sic! var store = new mongostore({db: mongoose.connection.db}, resulthandler); 

you can see whole code @ github.
here minified version of main script there:

var express = require('express'),     mongoose = require('mongoose')     mongostore = require('connect-mongodb');  var app = express(); var mongourl = 'mongodb://localhost/problem_users'; var port = 9001;  console.log('connecting mongodb...'); mongoose.connect(mongourl);  schema = mongoose.schema;  attributes = {   email: {     type: string,     required: true,     unique: true   } };  schema = new schema(attributes, {   strict: true });  var user = mongoose.model('user', schema);  app.configure(function() {    app.use(express.cookieparser());    app.use(express.session({     secret: 'what bad can happen if share secret?',     maxage: new date(date.now() + 60*60*1000),     store: new mongostore({       db: mongoose.connection.db     }, function(err) {       return console.log(err || 'connect-mongodb setup ok');     })   }));    return app; });  app.get('/', function(req, res) {   console.log('ready register new user...');    var userpropertiesdict = {     email: 'some.email@example.com',   }    console.log('calling user.create...');   user.create(userpropertiesdict, function(err, doc) {      console.log('why message not printed @ all?');     var done = process.stdout.write('are stuck @ flushing?');     if (!done) { // stdout blocked?       process.stdout.on('drain', _)     }    });   console.log('response over. message printed @ end , hang afterwards.'); });  app.listen(port); console.log("listening on port ", port); console.log("mongodb url ", mongourl); console.log('navigate browser http://localhost:%d', port); 

note problem includes connect-mongodb, not connect-mongo. switching connect-mongodb connect-mongo resolves problem in more elegant way, should try first. following related connect-mongodb only.

i have figured out problem doesn't involve express @ all. deals order in mongoose connection , connect-mongodb session initialized.

when connect-mongodb session initialized, database must connected. mongoose.connect executed asynchronously can easy run problem when session initialized bofore connection finished (as did).

the sad side reason connect-mongodb doesn't throw or pass error.

you can see right , wrong ways of mongoose , connect-mongodb initializion in code below.

var mongoose = require('mongoose')     mongostore = require('connect-mongodb');  var mongourl = 'mongodb://localhost/problem_users';  console.log("mongodb: url ", mongourl); console.log('mongodb: connecting...');  /* // wrong way of using mongoose connect-mongodb. // source below source of problem.  mongoose.connect(mongourl, function(err) {   console.log('this not printed.');   if (err) {     console.log('this not printed either.');     throw err;   } });  new mongostore({   db: mongoose.connection.db }, function(err) {   // line below prints 2.   console.log('mongodb: readystate %d (2 = connecting, 1 = connected)', mongoose.connection.readystate);   return console.log(err || 'connect-mongodb setup ok'); }) */  // right way of using mongoose connect-mongodb. mongoose.connect(mongourl, {auto_reconnect: true, native_parser: true}, function(err) {   new mongostore({     db: mongoose.connection.db   }, function(err) {     // line below usuall prints 1.     console.log('mongodb: readystate %d (2 = connecting, 1 = connected)', mongoose.connection.readystate);     return console.log(err || 'connect-mongodb setup ok');   }); });  console.log('mongodb: connected.')  schema = mongoose.schema;  attributes = {   email: {     type: string,     required: true,     unique: true   } };  var schema = new schema(attributes);  var user = mongoose.model('user', schema);  function createuser(callback) {    var userpropertiesdict = {     email: 'some.email@example.com',   }    console.log('calling user.create...');   user.create(userpropertiesdict, callback); }  function never_called_callback(err, doc) {      console.log('why message not printed @ all?');     var done = process.stdout.write('are stuck @ flushing?');     if (!done) { // stdout blocked?       process.stdout.on('drain', _)     } }  createuser(never_called_callback); // either creates new user or logs error exists. 

also see this article helped me settle things right way.