Best way to store date/time in mongodb

Question

The best way is to store native JavaScript Date objects, which map onto BSON native Date objects.

> db.test.insert({date: ISODate()})
> db.test.insert({date: new Date()})
> db.test.find()
{ "_id" : ObjectId("..."), "date" : ISODate("2014-02-10T10:50:42.389Z") }
{ "_id" : ObjectId("..."), "date" : ISODate("2014-02-10T10:50:57.240Z") }

The native type supports a whole range of useful methods out of the box, which you can use in your map-reduce jobs, for example.

If you need to, you can easily convert Date objects to and from Unix timestamps¹⁾, using the getTime() method and Date(milliseconds) constructor, respectively.

¹⁾ Strictly speaking, the Unix timestamp is measured in seconds. The JavaScript Date object measures in milliseconds since the Unix epoch.

One datestamp is already in the _id object, representing insert time

So if the insert time is what you need, it's already there:

Login to mongodb shell

ubuntu@ip-10-0-1-223:~$ mongo 10.0.1.223
MongoDB shell version: 2.4.9
connecting to: 10.0.1.223/test

Create your database by inserting items

> db.penguins.insert({"penguin": "skipper"})
> db.penguins.insert({"penguin": "kowalski"})
> 

Lets make that database the one we are on now

> use penguins
switched to db penguins

Get the rows back:

> db.penguins.find()
{ "_id" : ObjectId("5498da1bf83a61f58ef6c6d5"), "penguin" : "skipper" }
{ "_id" : ObjectId("5498da28f83a61f58ef6c6d6"), "penguin" : "kowalski" }

Get each row in yyyy-MM-dd HH:mm:ss format:

> db.penguins.find().forEach(function (doc){ d = doc._id.getTimestamp(); print(d.getFullYear()+"-"+(d.getMonth()+1)+"-"+d.getDate() + " " + d.getHours() + ":" + d.getMinutes() + ":" + d.getSeconds()) })
2014-12-23 3:4:41
2014-12-23 3:4:53

If that last one-liner confuses you I have a walkthrough on how that works here: https://stackoverflow.com/a/27613766/445131