Versioning does not work if the versionKey option for toObject is set to false when using insertMany

[juona]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

8.1.1

Node.js version

18.18.2

MongoDB server version

5

Typescript version (if applicable)

No response

Description

Quite a specific issue here...

Setting the schema option toObject to { versionKey: false } interferes with the versioning mechanism when Model.prototype.insertMany() is used. This affects optimisticConcurrency too.

Debug logs print:

Mongoose: mymodels.insertMany([ { name: 'x', _id: new ObjectId('65c6b71554b43144d136c12f') } ], {})

Using Model.prototype.create() works correctly:

Mongoose: mymodels.insertOne({ name: 'x', _id: ObjectId("65c6b745afcd1f760cc117ba"), __v: 0 }, {})

Not surprising since the logic for the two methods is deliberately completely separate. Just makes me wonder if there are more edge cases like this one? I.e. what are some other ways of inserting a new document into the database that might not be covered? Perhaps this is something worth looking into.

Steps to Reproduce

import mongoose from "mongoose";
import { MongoMemoryReplSet } from "mongodb-memory-server";

console.log("connecting...");

const mongoDbService = await MongoMemoryReplSet.create();
await mongoose.connect(mongoDbService.getUri());

console.log("connected!");

const schema = new mongoose.Schema(
  { name: String },
  // Could be `optimisticConcurrency` as well
  { versionKey: "__v", toObject: { versionKey: false } }
);

const Model = mongoose.model("MyModel", schema);

// Substituting this for `create()` fixes the problem
await Model.insertMany([{ name: "x" }]);

const doc = await Model.findOne();

console.log(doc.__v); // prints `undefined` when using `insertMany`, and `1` when using `create`

await mongoose.disconnect();

console.log("done!")

process.exit(0);

Expected Behavior

My reasoning is that I set toObject: { versionKey: false } because I don't wish to have this field in the output when I invoke toObject(). I don't believe it should affect the internal mechanics of the versioning feature though.

[donoftime2018]

https://mongoosejs.com/docs/guide.html#versionKey

According to the documentation, you shouldn't be putting versionKey inside toObject. You should put it in the Schema definition like

const schema = new mongoose.Schema(
  { name: String },
  // Could be `optimisticConcurrency` as well
  { versionKey: false } //defaults to __v 
);

[IslandRhythms]

const mongoose = require('mongoose');

const testSchema = new mongoose.Schema(
  { name: String },
  // Could be `optimisticConcurrency` as well
  { versionKey: "__v", toObject: { versionKey: false } }
);

const Test = mongoose.model("Test", testSchema);

async function run() {
  await mongoose.connect('mongodb://localhost:27017');
  await mongoose.connection.dropDatabase();

  await Test.insertMany([{ name: 'x' }]);

  const doc = await Test.findOne();

  console.log(doc.__v);

  console.log('done');
}

run();

[donoftime2018]

@juona Does this solve your problem for now?

#!/usr/bin/env node
const mongoose = require('mongoose');

const testSchema = new mongoose.Schema(
  { name: String },
  // Could be `optimisticConcurrency` as well
  { versionKey: '__v' }
);

// testSchema.set('__v', false) //sets __v to 0 commented out or not

const Test = mongoose.model("Test", testSchema);

async function run() {
  await mongoose.connect('mongodb://localhost:27017');
  await mongoose.connection.dropDatabase();

  await Test.insertMany([{ name: 'x' }]);

  const doc = await Test.findOne();

  console.log(doc.__v); // 0

  console.log('done');

  process.exit(0)
}

run();

[juona]

@donoftime2018 Thanks for the help. This was not a burning issue, I just used Model.prototype.create() instead. I will give your method a try in case there is a real need to use insertMany (still on v7, you see, so this fix probably does not apply).

@vkarpov15 Thanks, swift as always!