Meteor, MongoDb: Double inserting to collection on few occurences - node.js

Question

I noticed this strange behaviour, when for few users only on production, it inserts every item multiple times to collection on asynchronous Meteor call. I tried multiple things, but nothing worked. I can't test on localhost, bc it never happens to me on localhost or in production.
I spent the whole night solving this, but didn't find any solution. I suppose it's caused by new Date(), but I have to call it somewhere. The production server is in Amsterdam and it seems like it happens only for users located further outside of Europe.
I found this to be similar issue, but can't really wrap my head on how to implement - https://github.com/meteor/meteor/issues/4263
Slug is what same songs are supposed to have the same.
This is the workflow, user clicks on song that triggers addNewSong function:
addNewSong = function (track) {
Globals.current_track = track;
checkIfSongAlreadySaved();
}
I need to check if song is already in collection, if it's -> route to it, else create the new song and route to it.
checkIfSongAlreadySaved = function() {
loadPrimaryGlobalItems();
Meteor.call('checkIfSongAlreadySaved', Globals.current_song_item_slug, function(error, result) {
if( result.item ) {
Globals.current_song_item_id = result.item._id;
Globals.current_song_item_slug = result.item.slug;
routeToSongPage();
if (! (result.item.download && result.item.mp3) ) {
downloadSong();
}
}
else {
loadSecondaryGlobalItems();
var item = {
slug:Globals.current_song_item_slug,
duration:Globals.current_duration,
thumbnail:Globals.current_song_thumbnail,
title:Globals.current_cleaned_song,
album:Globals.current_track.album,
artist:Globals.current_track.artists[0],
track:Globals.current_track.name,
date:result.date,
}
Globals.current_song_item_id = Songs.insert(item);
routeToSongPage();
downloadSong();
recentSongItem(result.date);
}
});
}
Add recent song
recentSongItem = function (date) {
Recentsongs.insert({
slug:Globals.current_song_item_slug,
songId:Globals.current_song_item_id,
title:Globals.current_cleaned_song,
duration:Globals.current_duration,
date:date,
});
}
If creating new song,
downloadSong = function() {
Meteor.call('findSong', Globals.current_song, function(error, result) {
console.log(result);
if (result) {
Globals.current_song_mp3 = true;
updateSongItemDownload(result.itemDetails);
}
else {
alert('not found')
}
});
}
and update song, to add download and mp3 values.
updateSongItemDownload = function(link) {
Songs.update({
_id: Globals.current_song_item_id
},
{
$set: {
download: link,
mp3: Globals.current_song_mp3,
}
});
}
Server methods:
Meteor.methods({
checkIfSongAlreadySaved: function(slug) {
return {item: Songs.findOne({slug:slug}), date: new Date()};
},
findSong:function(song) {
ServerGlobals.current_song = song;
var result = searchSite();
return result;
},
});
EDIT:
This is my subscription, just in case it might be causing the problem:
Template.songPage.onCreated(function() {
Session.set('processing', true);
var self = this;
self.autorun(function() {
var id = Router.current().params.id;
self.subscribe('singleSong', id);
var item = Songs.findOne({_id: id});
if (item) {
if (item.download) {
createSong(item.download);
}
else if( item.download === false ) {
console.log('item not found');
}
Session.set('loader', false);
Session.set('processing', false);
}
});
});
Meteor.publish('singleSong', function(id) {
check(id, String);
return Songs.find({_id: id});
});

Answer 1

You can apply a unique index on the slug field to ensure the same slug can only exist once and the second operation to insert will fail and show up as an error in your callback which you can discard or alert user as you desire.
db.collection.createIndex( { slug: 1 }, { unique: true } )
You will need to clear or modify the slug name on the dups from the db before applying the index though