MongoDB ObjectId ↔ Timestamp Converter

Did you know that each MongoDB ObjectId contains an embedded timestamp of its creation time?

From the mongo shell, you can use getTimestamp() to retrieve the timestamp from the ObjectId, but there's no built in function to generate an ObjectId from a timestamp.

This online converter will convert from timestamp to ObjectId and vice versa.

Why generate an ObjectId from a timestamp?

To query documents by creation date.

e.g. to find all users created after 2017-12-01 , here users is a collection in mongodb

db.users.find({_id: {$gt: ObjectId("5a204e280000000000000000")}})

Javascript functions to generage objectId from date

var objectIdFromDate = function (date) {
	return Math.floor(date.getTime() / 1000).toString(16) + "0000000000000000";
};

Javascript functions to generage date from objectId

var objectIdFromDate = function (date) {
	return Math.floor(date.getTime() / 1000).toString(16) + "0000000000000000";
};

var dateFromObjectId = function (objectId) {
	return new Date(parseInt(objectId.substring(0, 8), 16) * 1000);
};