How to convert from Timestamp to Mongo ObjectID

Question

I know that we can use getTimestamp() to retrieve the timestamp from the ObjectId, but is there any way to generate an ObjectId from a timestamp?

More specifically, if I have an input of month and year, then I want to convert it into Mongo ObjectID to query in db, how should I do this?

Possible duplicate of [Mongodb: Perform a Date range query from the ObjectId in the mongo shell](https://stackoverflow.com/questions/13593896/mongodb-perform-a-date-range-query-from-the-objectid-in-the-mongo-shell) — Mohammed Essehemy, Sep 23 '17 at 11:22
No that is a different answer, this is if we want to convert a timestamp to objectID where you want the objectID to contain a certain date/time, not necessarily the current datetime — Sharjeel Ahmed, Nov 13 '17 at 14:16

score 19 · Accepted Answer · answered Feb 02 '18 at 18:50

19

try this,

> ObjectId("5a682326bf8380e6e6584ba5").getTimestamp()
ISODate("2018-01-24T06:09:42Z")
> ObjectId.fromDate(ISODate("2018-01-24T06:09:42Z"))
ObjectId("5a6823260000000000000000")

Works from mongo shell.

answered Feb 02 '18 at 18:50

vkrishna

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never understood why the [MongoDB docs](https://www.mongodb.com/docs/v5.0/reference/method/ObjectId/#methods-and-attributes) don't list the `fromDate` function. thank you so much! – asgs Dec 13 '22 at 16:55

Derek Hill · Answer 2 · 2019-02-12T16:41:23.137

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If you pass a number to the bson ObjectId constructor it will take that as a timestamp and pass it to the generate method.

You can get a Date from a month and year per this answer (months start at zero).

So:

timestamp = ~~(new Date(2016, 11, 17) / 1000)
new ObjectId(timestamp)

edited Feb 12 '19 at 16:41

answered Feb 12 '19 at 16:28

Derek Hill

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score 2 · Answer 3 · answered Jul 19 '17 at 13:43

2

Yes you can:

dummy_id = ObjectId.from_datetime(gen_time)

Where gen_time is datetime.

answered Jul 19 '17 at 13:43

svink

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I think `from_datetime` is PyMongo equivalent, so it won't work in MongoDB shell. the [answer from vkrishna](https://stackoverflow.com/questions/38629868/how-to-convert-from-timestamp-to-mongo-objectid#answer-48589096) mentions the `fromDate` method – asgs Jun 10 '22 at 11:28

score -3 · Answer 4 · answered Jul 28 '16 at 07:41

An ObjectId() is a 12-byte BSON type and consists of:

The first 4 bytes representing the seconds since the unix epoch
The next 3 bytes are the machine identifier
The next 2 bytes consists of process id
The last 3 bytes are a random counter value

Clearly, you will not be able to create ObjectId() only from timestamp.

How to convert from Timestamp to Mongo ObjectID

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