moment.utc drops time part when used default

[ErikaA4]

Describe the bug
When we create a date field and default it to moment.utc, when it gets populated the date part of the timestamp is correct, but the time part gets lost and defaulted to midnight.

To Reproduce
Steps to reproduce the behavior:
Run the attached script.

const mongoose = require('mongoose');
const moment = require('moment');

main().catch(err => console.log(err)).then();

async function main() {
  await mongoose.connect('mongodb://localhost:27017/test');

  const kittySchema = new mongoose.Schema({
    birthday: {default: moment.utc, type: Date}
  });

  const Kitten = mongoose.model('Kitten', kittySchema);

  const cat = new Kitten({});
  console.log(cat);
 }

Expected behavior
Timestamp to be set to now with hour, minute and second correctly displayed (not zero).
Got this:

Erikas-Macbook:BUG erikaarnocki$ ts-node bug.ts
{
  _id: new ObjectId("61e5471c712520a0f39ebbef"),
  birthday: 2022-01-17T00:00:00.000Z
}

Expected:

Erikas-Macbook:BUG erikaarnocki$ ts-node bug.ts
{
  _id: new ObjectId("61e5471c712520a0f39ebbef"),
  birthday: 2022-01-17T10:39:40.000Z
}

Desktop:

• ts-node v8.10.2

Moment-specific environment

• The time zone setting of the machine the code is running on

Erikas-Macbook:BUG erikaarnocki$ locale
LANG="en_GB.UTF-8"
LC_COLLATE="en_GB.UTF-8"
LC_CTYPE="en_GB.UTF-8"
LC_MESSAGES="en_GB.UTF-8"
LC_MONETARY="en_GB.UTF-8"
LC_NUMERIC="en_GB.UTF-8"
LC_TIME="en_GB.UTF-8"
LC_ALL=

• The time and date at which the code was run
  Mon 17 Jan 2022 10:32:37 GMT
• Other libraries in use (TypeScript, Immutable.js, etc)

{
  "devDependencies": {
    "@types/node": "^17.0.9",
    "cypress-wait-until": "^1.7.1"
  },
  "dependencies": {
    "moment": "^2.29.1",
    "mongoose": "^6.1.6",
    "typescript": "^4.5.4"
  }
}

Please run the following code in your environment and include the output:

console.log((new Date()).toString())
console.log((new Date()).toLocaleString())
console.log((new Date()).getTimezoneOffset())
console.log(navigator.userAgent)
console.log(moment.version)

Erikas-Macbook:BUG erikaarnocki$ ts-node
> console.log((new Date()).toString())
Mon Jan 17 2022 10:33:56 GMT+0000 (Greenwich Mean Time)
undefined
> console.log((new Date()).toLocaleString())
17/01/2022, 10:33:56
undefined
> console.log((new Date()).getTimezoneOffset())
0
undefined
> console.log(navigator.userAgent)
/Users/erikaarnocki/BUG/[eval].ts:1
console.log(navigator.userAgent);
            ^

Uncaught ReferenceError: navigator is not defined
    at /Users/erikaarnocki/BUG/[eval].ts:1:13
    at Script.runInThisContext (vm.js:133:18)
    at exec (/usr/local/lib/node_modules/ts-node/src/bin.ts:347:17)
    at /usr/local/lib/node_modules/ts-node/src/bin.ts:337:27
    at Array.reduce (<anonymous>)
    at _eval (/usr/local/lib/node_modules/ts-node/src/bin.ts:336:18)
    at REPLServer.replEval (/usr/local/lib/node_modules/ts-node/src/bin.ts:387:16)
    at bound (domain.js:413:15)
    at REPLServer.runBound [as eval] (domain.js:424:12)
    at REPLServer.onLine (repl.js:817:10)

[ErikaA4]

Opened ticket to moment as well.
moment/moment#5966

[Maximusya]

Just a guess:

1. you are using default: moment.utc in your schema: that's a function accepting some doc object (as per https://mongoosejs.com/docs/migrating_to_6.html#document-parameter-to-default-functions)
2. moment.utc(obj) expects year, month etc fields in an object argument (per https://momentjs.com/docs/#/parsing/object/). Omitted units default to 0 or the current date, month, and year.

So this schema definition might work for you:

  const kittySchema = new mongoose.Schema({
    birthday: {default: () => moment.utc(), type: Date}
  });

[Uzlopak]

@Maximusya
Semantically it is imho no difference.

Maybe there is a conversion issue. Probably it does a .toString, of the Moment-Object, which results in loss of milliseconds.Then it should be actually

birthday: {default: () => moment.utc().toDate(), type: Date}

[Maximusya]

What I meant is here: https://jsfiddle.net/n3vj01ax/:

console.log(moment.utc().toString());
console.log(moment.utc({ foo: 1 }).toString());

"Mon Jan 17 2022 15:17:25 GMT+0000"
"Mon Jan 17 2022 00:00:00 GMT+0000"

[AbdelrahmanHafez]

As the comments have pointed out, you need to change default: moment.utc to default: () => moment.utc(), that's a breaking change in mongoose v6.

  const kittySchema = new mongoose.Schema({
    birthday: { default: moment.utc, type: Date }
  });
  //   birthday: 2022-01-18T00:00:00.000Z

  const kittySchema = new mongoose.Schema({
    birthday: { default: () => moment.utc(), type: Date }
  });
  //   birthday: 2022-01-18T12:41:43.889Z

[ErikaA4]

Thanks all for the help!
This worked perfectly:
birthday: {default: (): Date => moment.utc().toDate(), type: Date}