Converting isodate to numerical value

Question

I am performing tests to ensure I'm getting the dates correctly.

My current tests are: pick a date in mongodb ISODate format and transform it to the numerical value (milliseconds since 1970) and vice versa

Example:

var date_test = ISODate ("2013-07-26T22:35:40.373Z")

What is the numeric value of this date? Which command is used to get this?

Answer 1

Starting Mongo 4.0, the $toLong aggregation operator can be applied on a Date to get a timestamp:

// { mydate: ISODate("2019-06-23T15:52:29.576Z")
db.collection.aggregate({ $project: { timestamp: { $toLong: "$mydate" } } })
// { timestamp: NumberLong("1561305149576") }

and vice versa with $toDate:

// { timestamp: NumberLong("1561305149576") }
db.collection.aggregate({ $project: { mydate: { $toDate: "$timestamp" } } })
// { mydate: ISODate("2019-06-23T15:52:29.576Z") }