Not able to connect to databse using nodejs

Question

Not able to connect to databse using nodejs

I am very new to nodejs and am not able to figure out what exactly is going on here- i have a basic login page, in which as the user types in the values, i go to the home page, before which i check up on the database if that username exists or not. The problem i am having is that when i click on the submit button, the code never seems to reach the database function.
This is my module in app.js -

app.post('/home',function(req,res){
        //check for user existence....
        var str;
        console.log("in home");
        user_login.perform_login(req.body.username,function(err,str){
            if(!err){
                console.log(str+" in login");
                var cookie_val=req.body.username;
                res.cookie('username',cookie_val,{signed: true});
                req.session.username=cookie_val;
                res.render('home.ejs',{
                    layout: false,
                    locals: {varname: cookie_val},
                    udata: req.session.username
                });
            }
            else{   
                console.log("Couldn't find it.");
                res.redirect("/login");
            }
        });
});

This is the perform_login from user_login.js-

var mongo_db=require("./testdb.js");
exports.perform_login=function (username,callback){
    mongo_db.getInfo(username,function(err,bundle){
        if(!err){
            //console.log("success\n"+bundle);
            callback(false,bundle);
        }
        else{
            //console.log("couldn't find it");
            callback(true,null);
        }
    });
}

and this is the testdb.js-

var mongoose=require('mongoose');
mongoose.connect('mongodb://localhost/test');
exports.getInfo=function(value,callback){
    var db=mongoose.connection;
    db.on('error',console.error.bind(console,'connection error:'));
    db.once('open',function(){
        console.log("Connected!");
        var userSchema=mongoose.Schema({
            username:       String,
            password:   String
        });
        var userInstances=mongoose.model('userInstances',userSchema);
        userInstances.findOne({username: value},'username password',function(err,ui){
                                if(!err){
                                    callback(false,ui);
                                }
                                else{
                                    callback(true,"error");
                                }
                            });//findone

    });//db.once function
}//getinfo

In the terminal i only get -"in home", after which nothing happens at all.In the browser, it seems to be processing but remains in the login page.
when i run the perform_login with an actual hard-coded value instead of req.body.username, immediately as app.js is launched, i get the proper results. So i am able to access the database somehow outside app.post().
Is there something wrong in the callbacks??

node.js
mongodb
express

Answer 1

I think that you are doing a bit too much here. The symptoms you are describing are in my experience from a not connected mongoose. You do not need to manage the connection and listen on events, if it is connected. Mongoose handles this for you. You can query a model and it will return the result as soon the connection is established.

Here is an example that should work:

app.js
//initialize mongo connection
var mongooseConnection = mongoose.connect("mongodb://localhost/test");


user.js
var mongoose = require('mongoose');
var userSchema=mongoose.Schema({
    username:       String,
    password:   String
});

userSchema.statics.performLogin = function(username, callback) {
    this.findOne({username: value},'username password',function(err,user){
    if(!err){
        callback(false,user);
    }
    else{
        callback(true,"error");
    }
});

module.exports = mongoose.model('users',userSchema);


route:
var User = require("./user");
app.post('/home',function(req,res){
    User.performLogin(req.body.username, function (err, user) {
        ...
    });
});