saving a clientside date as UTC date object into Mongo - mongodb

Question

I am trying to save a date into meteor mongodb my challenge is as follows:
1) if i use new Date() it creates a date object in mongo DB however it saves the time as local time as javascript Date() this always comes with a timezone +0x:hours based on browser local timezone. When i retrieve this it causes havoc as i am assuming everything in my db is UTC.
2) I want to use moment js library which is great because it can represent dates in UTC properly but my challenge is how do i get mongo db to accept a moment time? The minute i use moment.format() it saves it as a string!
So how can i send a date to a mongodb insert command with a date object that is in UTC? string just dont work :(
Any help would be appreciated.
Thanks

Answer 1

I think everything you need to know about both of these questions can be found here and here.
TLDR:
If you directly insert/update from the client you will store a timestamp based on the user's clock. It will still be stored as UTC, but you may or may not want to trust that the time is correct. I strongly suggest using a method for any db modifications which involve time so that the server's version of time will always be used.
Moment objects are not serializable to a format compatible with mongodb. Use a date object and format it on the client.

Answer 2

The problem with saving dates on the client is that each client can have a different time zone, or even wrong time set. Thus the only solution is to have the date set on the server. Using a method for each insert / update is not an elegant solution.
A common practice is to modify the document inside allow or deny callback:
Messages.allow({
insert: function(userId, doc) {
...
doc.timestamp = new Date();
return true;
},
});
That way you ensure all documents have a compatible timestamp, and you can use usual db methods on the client.

Answer 3

The Meteor community recently started an extensive document about how to use dates and times. You'll find a lot of useful information there, in addition to David Weldon's links:
https://meteor.hackpad.com/Meteor-Cookbook-Using-Dates-and-Times-qSQCGFc06gH
However, in particular I recommend using https://github.com/mizzao/meteor-timesync when security is not a concern. It allows you to client-locally obtain an accurate server time even if the client's clock is way off, without a round-trip to the server. This can be useful for all kinds of reasons - in my apps, I universally just use server-relative time and don't care about what the client's time is at all.