How to use connection file of mongo db in other files of node.js application

Question

I have a file, connection.js that I want to use in another file. How can I use this file in another file for inserting and updating a database. For example I have another file named item.js in which I want to add the item details into the database.

var mongodb = require('mongodb');

module.exports = function() {

    this.getConnection = function(callback) {

        var MongoClient = mongodb.MongoClient;
        var url = 'mongodb://localhost:27017/ShoppingCart';

        console.log(url);

        MongoClient.connect(url, function(err, db) {

            if (err) {
                console.log('Unable to connect to the mongoDB server. Error:', err);
                return;
            } else {
                console.log('Connection established to', url);
                return callback;
            } //else

        }); //MongoClient.connect

    }; //Connection

}; //constructor

item.js

In this file the addItem function takes a JSON object which I want to store in the database. For that I need to connect to the database and then insert the result, but I don't understand how to connect to the database.

I tried this but it's not working:

 /**
  * Shopping Cart
  * @author Sunil Hirole
  * @Date 15-july-2015
  * This is an e-commerce application for purchasing items
  */

var prompt = require('prompt');
var item = require('../models/itemArray.js');
var Connection = require('../util/con.js');

/** 
  * Item class is a model class
  * It contains addItem,editItem,showItem,deleteItem functions 
 */

function Item(){
    this.id;
    this.name;
    this.price;
}//Item 

/**
  *addItem Function 
  **/

Item.prototype.addItem = function(result){
var connection = new Connection();
var db = connection.getConnection(function(err,db){});
var Collection = db.collection('ItemsArray');
Collection.insert([result], function(err, result) {
    if (err) {
        console.log(err);
        return;
        } 
    else {
        return result;
        }
//Close connection
db.close();
 });
  return(result);
  }//addItem

Answer 1

hello just try exporting the callback function in your line you have

module.exports = function(callback) {

    var MongoClient = mongodb.MongoClient;
    var url = 'mongodb://localhost:27017/ShoppingCart';
    MongoClient.connect(url, callback)

instead of function(err, db) use the callback MongoClient.connect(url, callback);

latter in your item.js just use the connection var

var connection = require('../util/con.js');

// the rest of the file here

connection(function(err,db){
    db.collection('ItemsArray').
    insert([result], function(err, result) {
     if (err) {
        console.log(err);
       return;
     } 
     else {
        return result;
     }
//Close connection
});