assign() on JSON property fails when persisting with MongoDB driver

[alexandre-abrioux]

Describe the bug

Hi! First of all, thank you for maintaining the best ORM/ODM for NodeJS 🙂

While migrating a project from v5 to v6, I noticed some inconsistencies with persisting JSON properties.

Using bisection, I've identified that version 5.6.10 introduced a regression/bug. I'm not sure which commit precisely, but you can find the list here.

The issue is the following: When updating a JSON property using assign(), the change is not persisted in the database.

While digging a bit more, I discovered that the __originalEntityData wrapper property is also updated with assign(), thus preventing the changeset from being computed at commit time.

More info:

• When updating the property with a brand new object, it works. The issue is only present with assign().
• I confirmed the issue with the MongoDB driver but not with the SQLite driver, it seems to work fine with SQLite.

Reproduction

Here is a test case to reproduce the issue: https://github.com/alexandre-abrioux/mikro-orm-issue-5158

What driver are you using?

@mikro-orm/mongodb

MikroORM version

6.0.5

Node.js version

18.18.0

Operating system

No response

Validations

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• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
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• The provided reproduction is a minimal reproducible example of the bug.

[alexandre-abrioux]

Thank you @B4nan 🙂