Mongo DB ObjectId

_id is 12 bytes and

• first 4 bytes are timestamp
• next 3 bytes Machine identifier
• next 2 bytes process identifier
• last 3 bytes counter

if only we record more than 16 million records on the same machine same processor and same second then id will not be unique

id is generated by driver not by MongoDB

Generating id manually

const mongoose = require('mongoose');
const id = new mongoose.Types.ObjectId();
console.log(id);

extract timestamp from id

console.log(id.getTimestamp());

Checking validation of the Object Id

const isValid = mongoose.Types.ObjectId.isValid('1234');
console.log(idValid);

joi-objectid

To validate ObjectIDs using joi, use joi-objectid NPM package.