how to create a new collection automatically in mongodb - node.js

Question

my main issue is how do this architecture - if a user creates a new list in database and there is a separate collections for storing lists ,then i should redirect him when he want to access a specific list where he can store his contacts by assigning him some collection in database, now the problem comes for me, if there are 'n' lists of a specific user for saving his contacts by categorizing in to lists based on his need , then how should i implement this architecture any suggestions ? or there's a mistake with what i have done so far ? any corrections ?
i am using mongodb,nodejs with express framework
What i have so far done is manually i was able to create a new list and allocate a collection for it so that user can add his contacts in that list.
But creating collections manually for each and every list is not possible so i am searching for a method where we can automatically create a new collection on demand.
Is there any method to create n collection or n sub collections in mongodb ?
This is my js file for adding contacts in a collection , where i have stored those contacts in two separate list with separate collection for each list.
var express = require('express');
var router = express.Router();
var $ = require("jquery");
var mongoose = require('mongoose');
/* GET New User page. in list 1 */
router.get('/mylist', function(req, res) {
res.render('mylist', { title: 'Go To My-List' });
});
router.post('/delcontact', function(req, res){
console.log('Using delcontact');
var db = req.db;
var collection = db.get('golists');
console.log('Got this : ' + JSON.stringify(req.body));
var delcontact = req.body;
var emails = Object.keys(delcontact).map(function(k) { return delcontact[k] });
for(var z=0; z<emails.length; z++){
//console.log('email: \n' + emails[z]);
collection.remove({email: emails[z]},
function(err, doc, z) {
if (err)
res.send('delete unsuccessfull');
else {
console.log('Selected contacts deleted');
}
});
res.send({redirect: '/userlist2'});
var collection = db.get('golists');
};
});
/* POST to Add User Service */
router.post('/addusers', function(req, res) {
// Set our internal DB variable
var db = req.db;
// Get our form values. These rely on the "name" attributes
var firstName = req.body.firstname;
var lastName = req.body.lastname
var userEmail = req.body.useremail;
// Set our collection
var collection = db.get('golists');
// Submit to the DB
collection.insert({
"firstname" : firstName,
"lastname" : lastName,
"email" : userEmail
}, function (err, doc) {
if (err) {
// If it failed, return error
res.send("There was a problem adding the information to the database.");
}
else {
// If it worked, set the header so the address bar doesn't still say /adduser
res.location("mailinglist");
// And forward to success page
res.redirect("mailinglist");
}
});
});
/* GET Userlist page. */
router.get('/mailinglist', function(req, res) {
var db = req.db;
var collection = db.get('golists');
collection.find({},{},function(e,docs){
res.render('userlist2', {
"userlist2" : docs
});
});
});
/* this is for list 2 */
router.get('/mylist2', function(req, res) {
res.render('mylist2', { title: 'Go To My-List' });
});
router.post('/addusers2', function(req,res){
//Set our internal DB variable
var db = req.db;
// Get our form values. These rely on the "name" attributes
var firstName = req.body.firstname;
var lastName = req.body.lastname
var userEmail = req.body.useremail;
// Set our collection
var collection = db.get('golists2');
// Submit to the DB
collection.insert({
"firstname" : firstName,
"lastname" : lastName,
"email" : userEmail
}, function (err, doc) {
if (err) {
// If it failed, return error
res.send("There was a problem adding the information to the database.");
}
else {
// If it worked, set the header so the address bar doesn't still say /adduser
res.location("mailinglist2");
// And forward to success page
res.redirect("mailinglist2");
}
});
});
/* GET Userlist page. */
router.get('/mailinglist2', function(req, res) {
var db = req.db;
var collection = db.get('golists2');
collection.find({},{},function(e,docs){
res.render('mailinglist2', {
"mailinglist2" : docs
});
});
});
router.post('/delcontact2', function(req, res){
console.log('Using delcontact');
var db = req.db;
var collection = db.get('golists2');
console.log('Got this : ' + JSON.stringify(req.body));
var delcontact = req.body;
var emails = Object.keys(delcontact).map(function(k) { return delcontact[k] });
for(var z=0; z<emails.length; z++){
//console.log('email: \n' + emails[z]);
collection.remove({email: emails[z]},
function(err, doc, z) {
if (err)
res.send('delete unsuccessfull');
else {
console.log('Selected contacts deleted');
}
});
res.send({redirect: '/mailinglist2'});
var collection = db.get('golists2');
};
});
this is my file for creating new lists in some collection
router.get('/newlist',function(req,res){
res.render("newlist" ,{titile:'Add new list'}) ;
});
router.post('/addlist',function(req,res){
var db= req.db;
var listname=req.body.listname;
var collection=db.get("lists");
collection.insert({
"listname":listname
}, function (err,doc) {
if(err) {
res.send("There was a problem adding new list to database");
}
else {
res.location('lou');
res.redirect('lou');
}
});
});
router.get('/lou',function(req,res){
var db=req.db;
var collection=db.get("lists");
collection.find({},{},function(e,docs){
res.render('lou', {
"lou" : docs
});
});
});
router.get('/drop', function(req, res) {
res.render('drop', { title: 'Go To My-List' });
});
my jade file for this is
body
nav.navbar.navbar-default
.container-fluid
ul.nav.navbar-nav
li.active
a(href='/mailinglist')
| List 1
span.sr-only (current)
|
li
a(href='/mailinglist2')
| List 2
tbody
ul
p Import Contact From Your DB
a(href='/upload2') Go
table.table#stable
caption User Contact Details
|
thread
tr
th #
|
th FirstName
|
th LastName
|
th Email ID
|
each user, i in userlist2
tr(id=i)
td
input.contactID(type='checkbox')
td
| #{user.firstname}
td
| #{user.lastname}
td(id='email'+i)
| #{user.email}
button.btn.btn-danger#delete-button Delete Selected Contacts

Answer 1

First of all, this doesn't sound like a good idea. It would be much better when you have one collection for all lists of all users. The problem with having too many collections is that MongoDB doesn't offer any tools for selecting data from more than one collection at a time. So when you want to query data from multiple collections, you will have to perform multiple queries, which is very unperformant.
However, when you are determined to cling to this architecture, MongoDB automatically creates a collection when you insert data into a collection-name it doesn't know.