Create ObjectId in mongoose using a seed string

Question

I want to create an objectid in mongoose using a seed string eg-

Id = new ObjectId("alex"); 

Something on similar lines. But whatever examples I saw to generate the objectid require you to pass in the string in the objectid's hash format.

Is there a way to do what i want?

Answer 1

If anyone is still looking for a solution, the following gist may help.

import mongoose from "mongoose";
import RandomGenerator from "random-seed-generator";

const mockIt = (modifier = Math.random()) => {
  let mock = RandomGenerator.createWithSeeds("Mock" + modifier).hexString(24);
  return mock;
};

export const mockObjectId = (str, options) => {
  const { plainText = false } = options || {};
  const id = mongoose.Types.ObjectId(mockIt(str));
  return plainText ? id.toString() : id;
};

Answer 2

You can use this code

/**
 * https://docs.mongodb.com/manual/reference/method/ObjectId/
 * @param seed - string allowing to create predictable mongo id value ( the same for any execution )
 * @param date - date of creation - first 4 bytes of id
 * @returns {ObjectId}
 */
function mongoIdFromSeed(seed, date = "2022-01-01") {
  return new ObjectID(dayjs(date).unix().toString(16) + crypto.createHash("md5").update(seed).digest("hex").substr(0, 16));
}

for given seed and date you will obtain the same results any time.

---

This code depends on library dayjs you can remove this dependency using

new Date(date).getTime() / 1000 | 0

to instead of unix method. I mean

function mongoIdFromSeed(seed, date = "2022-01-01") {
  return new ObjectID((new Date(date).getTime() / 1000 | 0).toString(16) + crypto.createHash("md5").update(seed).digest("hex").substr(0, 16));
}