Is there a way to display timestamp in unix format to ISODate?

Question

We stored a date using unix timestamp in MongoDB, how do I get the date when I do the query? Is there a way to display timestamp in ISODate format?

Answer 1

Mongodb 4.0 has introduced $toDate aggregation, so you can try with it

db.collection.aggregate([
  { "$project": {
    "toDate": {
      "$toDate": "$unixTimestamp"
    }
  }}
])

Try it here

Answer 2

Background

• A unixtime value represents seconds since the epoch (Jan 1, 1970).

• A JavaScript Date() represents milliseconds since the epoch.

• In MongoDB, ISODate() is a convenience wrapper for Date() that allows you to create dates from ISO strings in the mongo shell. If you use new Date() in the shell, it will return an ISODate().

Conversion

To convert between a unixtime and an ISODate() you can multiply your unix timestamps by 1000 and pass this value to the new Date() constructor.

A simple example in the mongo shell:

> db.mydata.insert({
    unixtime: 1362143511
})

> var doc = db.mydata.findOne();

// convert unixtime seconds to milliseconds and create JS date
> var date = new Date(doc.unixtime * 1000);

> date
ISODate("2013-03-01T13:11:51Z")

Answer 3

In the Mongo console you can create a JavaScript Date object from a timestamp before the document is printed to the screen:

> db.stuff.find().forEach(function (doc) {
  doc["timestamp_field"] = new Date(doc["timestamp_field"])
  printjson(doc)
})

Be careful with that code, unlike a regular find() it will not page the results but print every matching document without pausing.