bulkSave promise result, updateResult.getWriteErrorCount is not a function

[kYem]

Prerequisites

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

Mongoose version

8.8.2

Node.js version

20.18.3

MongoDB server version

6.10.0

Typescript version (if applicable)

5.5.4

Description

This seems to only happen from time to time, maybe cause we are sending a large list of updates, potentially (1-5100) updates in bulk save.

    const updateResult = await TrackerValue.bulkSave(toUpdateValues);
   // Error updateResult.getWriteErrorCount is not a function
    result.failCount = updateResult.getWriteErrorCount();
    result.success = true;
    return result;

Steps to Reproduce

Unfortunately not easy way to produce. Will try to create separate isolated case, but hopefully even without it would be easy to narrow down when getWriteErrorCount is not a function

Expected Behavior

Should either throw error or TypeScrip types are not correct, as getWriteErrorCount is not always available?

[vkarpov15]

I'm unable to repro, the following script works as expected:

const mongoose = require('mongoose');

const trackerValueSchema = new mongoose.Schema({ value:{ type: Number, unique: true } });
const TrackerValue = mongoose.model('TrackerValue', trackerValueSchema);

(async () => {
  await mongoose.connect('mongodb://127.0.0.1:27017/test');
  await TrackerValue.deleteMany({});

  const docs = Array.from({ length: 5001 }, (_, i) => new TrackerValue({ value: i }));
  await TrackerValue.insertMany(docs);

  const toUpdateValues = await TrackerValue.find();
  toUpdateValues.forEach((doc) => (doc.value *= 5000));

  const updateResult = await TrackerValue.bulkSave(toUpdateValues);
  console.log(updateResult.getWriteErrorCount());

  await mongoose.disconnect();
})();

Are you passing options to bulkSave()? If you're not passing options to bulkSave() and not using bulkWrite middleware, I'm not sure this particular error is possible. We did find a potential edge case where bulkSave() can theoretically return null, but that wouldn't result in the error message you're seeing. Can you please modify the above repro script to try to demonstrate the issue you're seeing?

[kYem]

Nope, no options, only array of models to be saved.

• no middleware for bulkSave

It only happen a few times recently, that Sentry was able to catch, both cases indicate multiple request happening for the same model.

Given that the actual bulkSave can take 3-6s, it's likely that the same underlying documents are being updated in two separate request 🤔. Even though the logs indicate they are sequential.

Note that model is big, have embedded history within the document (so it can grow for frequently updated entries), it also the large collection, over 5 million documents, with a lot of indexes.

So it's not easy to reproduce, and it happens quite rarely as you can see, these are all the entries from Sentry we have.

I'm on holiday right now. I will try to spend more time on reproducible case once I'm back (10 days)

[vkarpov15]

@kYem can you please try upgrading to 8.12.2 and see if that upgrade fixes the issue?

[kYem]

Managed to reproduce and have two separate queries run, first one finish, second run the same action.

First run, remove user from survey

[] BulkWriteResult {
[]   insertedCount: 0,
[]   matchedCount: 553,
[]   modifiedCount: 553,
[]   deletedCount: 0,
[]   upsertedCount: 0,
[]   upsertedIds: {},
[]   insertedIds: {}
[] }

Second run, remove the same user on same survey
On failed version, the result is

[] {
[]   result: {
[]     ok: 1,
[]     writeErrors: [],
[]     writeConcernErrors: [],
[]     insertedIds: [],
[]     nInserted: 0,
[]     nUpserted: 0,
[]     nMatched: 0,
[]     nModified: 0,
[]     nRemoved: 0,
[]     upserted: []
[]   },
[]   insertedCount: 0,
[]   matchedCount: 0,
[]   modifiedCount: 0,
[]   deletedCount: 0,
[]   upsertedCount: 0,
[]   upsertedIds: {},
[]   insertedIds: {},
[]   n: 0
[] }

This happens when two request trigger a change to the same model.

@vkarpov15 anything come to mind? Is that because the second query does not actually have any updates triggered? as in the first

After updating to 8.12.2, it seems like the issue is fixed and I'm getting

First run

[] BulkWriteResult {
[]   insertedCount: 0,
[]   matchedCount: 553,
[]   modifiedCount: 553,
[]   deletedCount: 0,
[]   upsertedCount: 0,
[]   upsertedIds: {},
[]   insertedIds: {}
[] }

Second Run

[] BulkWriteResult {
[]   insertedCount: 0,
[]   matchedCount: 0,
[]   modifiedCount: 0,
[]   deletedCount: 0,
[]   upsertedCount: 0,
[]   upsertedIds: {},
[]   insertedIds: {},
[]   n: 0,
[]   mongoose: { validationErrors: [], results: [] }
[] }

Note that object is still different, but the underlying class is the same now, therefore there is no longer error.

Is that what you expected @vkarpov15 ?

[kYem]

Now it can be quite easily reproduced, by just removing update on your original script

const mongoose = require('mongoose');

const trackerValueSchema = new mongoose.Schema({ value:{ type: Number, unique: true } });
const TrackerValue = mongoose.model('TrackerValue', trackerValueSchema);

(async () => {
  await mongoose.connect('mongodb://127.0.0.1:27017/test');
  await TrackerValue.deleteMany({});

  const docs = Array.from({ length: 5001 }, (_, i) => new TrackerValue({ value: i }));
  await TrackerValue.insertMany(docs);

  const toUpdateValues = await TrackerValue.find();
  // No longer doing changes, just saving
  //  toUpdateValues.forEach((doc) => (doc.value *= 5000));

  const updateResult = await TrackerValue.bulkSave(toUpdateValues);
  console.log(updateResult.getWriteErrorCount());

  await mongoose.disconnect();
})();

[kYem]

Additional note, it seems this was no longer an issue since version 8.10.2, I assume likely it fixed as part of https://github.com/Automattic/mongoose/releases/tag/8.10.2

• fix(model+connection): return MongoDB BulkWriteResult instance even if no valid ops fix(model+connection): return MongoDB BulkWriteResult instance even if no valid ops #15266 Several issues with bulkWrite API exposing validation errors #15265

[vkarpov15]

Confirmed that this was fixed in 8.10.2, so I will close this issue.