feat: add index and doc to insertMany validation errors

[Jadu07]

This PR addresses feature request #14351 and introduces an enhancement for the insertMany() method when used with { ordered: false }
It adds two new properties to validation errors:

• error.index: the index of the failed document in the input array

These additions align Mongoose’s error reporting more closely with MongoDB’s native write errors and make debugging bulk inserts easier.

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Problem

Currently, when using insertMany() with { ordered: false, rawResult: true }, validation errors lack:

1. The index of the failed document in the original array

Without this, it’s difficult to identify and retry failed documents in production.

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Solution

Modified Model.$__insertMany() to add two properties to validation errors when ordered: false:

• error.index: The position of the failing document in the original array

Before:

{
  errors: {
    requiredField: {
      name: 'ValidatorError',
      message: 'requiredField is required.',
      // ...
    }
  },
  _message: 'User validation failed',
  name: 'ValidationError',
  message: 'User validation failed: requiredField: requiredField is required.'
}

After:

{
  errors: {
    requiredField: {
      name: 'ValidatorError',
      message: 'requiredField is required.',
      // ...
    }
  },
  index: 2,  // NEW: Position in the array
  _message: 'User validation failed',
  name: 'ValidationError',
  message: 'User validation failed: requiredField: requiredField is required.'
}

Testing

• All 3,943 existing tests pass
• Added 2 new test cases that verify:
  • index property matches the array position
  • Works with both rawResult and throwOnValidationError options

fixes #14351

[Jadu07]

Hey @vkarpov15 @hasezoey pls review this PR.

[hasezoey]

Looks good to me

[hasezoey]

Still looks good to me

[Copilot]

Pull Request Overview

This PR enhances the insertMany() method to add an index property to validation errors when using { ordered: false }. The addition helps developers identify which document in the input array failed validation, aligning with MongoDB's native error reporting pattern.

Key changes:

• Added index property to ValidationError type definition
• Modified validation error handling to set the index property in unordered inserts
• Added test coverage for the new index property in two scenarios

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
types/error.d.ts	Added optional index property to ValidationError type definition with JSDoc
lib/model.js	Set error.index during validation error handling for unordered inserts
test/model.insertMany.test.js	Added two test cases verifying index property with rawResult and throwOnValidationError options

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[vkarpov15]

Thanks 👍