Cannot read properties of undefined (reading '__data') when deleting an entity that uses the mappedBy option of OneToMany as 'owner'

[moowoonsunghoon]

Describe the bug
After updating to MikroORM 5.7.14, An error occurs when deleting an entity that uses the mappedBy option of OneToMany as 'owner'

Stack trace

import { Entity, ManyToOne, PrimaryKey, Property } from '@mikro-orm/core';

import { User } from './user.entity';

@Entity()
export class Team {
  @PrimaryKey({ columnType: 'uuid', defaultRaw: `gen_random_uuid()` })
  id!: string;

  @Property({ columnType: 'uuid', nullable: true })
  userId?: string;

  @ManyToOne(() => User, {
    fieldName: 'user_id',
    onUpdateIntegrity: 'set null',
    onDelete: 'cascade',
    nullable: true,
  })
  owner?: User;
}

import {
  Cascade,
  Collection,
  Entity,
  OneToMany,
  PrimaryKey,
} from '@mikro-orm/core';
import { Team } from './team.entity';

@Entity()
export class User {
  @PrimaryKey({ columnType: 'uuid', defaultRaw: `gen_random_uuid()` })
  id!: string;

  @OneToMany(() => Team, (team) => team.owner, {
    cascade: [Cascade.ALL],
  })
  teams = new Collection<Team>(this);
}

To Reproduce
Steps to reproduce the behavior:

1. create a OneToMany and ManyToOne relationShip with mappedBy use 'owner' string or entity.owner
2. Attempt to removeAndFlush entity with One relationship
3. Throws an error

Expected behavior
Data should be deleted normally.

Versions

Dependency	Version
node	16.18.1
typescript	5.1.3
mikro-orm	5.7.14
your-driver	"@mikro-orm/postgresql": "^5.7.14"

[B4nan]

Can you please provide a complete repro? So in addition to the entity definition, add also few lines that create some data and some that trigger this error. Entity definition does not reproduce much on its own.

[B4nan]

I see you are trying to map two persistent properties to a single db column (user and userId), this was never really supported. You should have only one, the relation property - you can access the FK without populating it. Or define the relation as non-persistent.

[moowoonsunghoon]

@B4nan
Thanks for the quick response!
The same error occurs after removing the userId property.
I've uploaded a reproduction repository
let me know if you have any trouble using it to reproduce the problem. Thanks again!

[B4nan]

Ok, this is quite a funny problem - it all boils down to your owning property being called owner which is the same as Collection.owner, an internal property. Because of this match, things got broken.

[moowoonsunghoon]

@B4nan
Thanks a lot for the quick fix!👍
May I know when the new version will be released?

[B4nan]

Use the dev version, I want to ship new feature release next, and still have few things I want to implement first. I hope stable will go out in the end of this week or during next week.