Is there a way to access a Date as milliseconds since epoch (Date.getTime()) in mongodb aggregation pipeline

Question

Mongodb provides lots of 'Date Aggregation Operators' such as $dayOfYear, $dayOf Month, and $millisecond. The $millisecond function just returns the milliseconds of the time stamp with a range of 0-999.

Is there a way to access a Date object as milliseconds since epoch in aggregation pipeline?

Thanks,

Nathan

Answer 1

You can $subtract the epoch date and the result will be your date milliseconds since epoch:

db.collection.aggregate([
    {$project : {
        "dateInMillis" : {$subtract : ["$date", new Date("1-1-1970")] }
    }}
]);