joinAndSelect does not include selected data in output

[tonyjaimep]

Describe the bug
joinAndSelect fields with ManyToOne relationships are not populated. Instead their PKs take their place.

Stack trace
None available

To Reproduce
Steps to reproduce the behavior:

1. In an EntityRepository add a method that uses qb() and joinAndSelect().
2. Use joinAndSelect to join and select a relationship (let's call it a).
3. Use joinAndSelect to join a select a manyToOne relationship field from that relationship (let's call it a.b).
4. Call the query.
5. a.b is not populated. Its primary key takes its place.

An example repository that does this is the one used in the example repository
https://github.com/tonyjaimep/mikro-orm-join-demo

import { EntityRepository } from '@mikro-orm/postgresql';
import { Author } from './author.entity';

export class AuthorRepository extends EntityRepository<Author> {
  async findAllWithRelations(userUuid: string): Promise<Author[]> {
    return this.qb()
      .select('*')
      .joinAndSelect('books', 'b')
      .joinAndSelect('b.template', 'bt')
      .leftJoinAndSelect('b.comments', 'bc', {
        'bc.userUuid': userUuid,
      });
  }
}

Expected behavior

Expected output (up until v5.5.3)

template and comments are populated

[
  {
    "uuid": "00000000-0000-0000-0000-000000000000",
    "name": "Test Author 1",
    "books": [
      {
        "uuid": "44444444-4444-4444-4444-444444444444",
        "title": "Test Book 1",
        "template": {
          "uuid": "22222222-2222-2222-2222-222222222222",
          "foo": "Test Book Template 1"
        },
        "author": "00000000-0000-0000-0000-000000000000",
        "comments": [
          {
            "uuid": "7d36d725-ab94-4324-b8ce-f2fac30964c2",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 2",
            "book": "44444444-4444-4444-4444-444444444444"
          },
          {
            "uuid": "b35373bb-fb4e-4818-bc58-8ffe691d25c7",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 1",
            "book": "44444444-4444-4444-4444-444444444444"
          }
        ]
      }
    ]
  },
  {
    "uuid": "11111111-1111-1111-1111-111111111111",
    "name": "Test Author 2",
    "books": [
      {
        "uuid": "55555555-5555-5555-5555-555555555555",
        "title": "Test Book 2",
        "template": {
          "uuid": "33333333-3333-3333-3333-333333333333", 
          "foo": "Test Book Template 2"
        },
        "author": "11111111-1111-1111-1111-111111111111",
        "comments": [
          {
            "uuid": "9bc6a377-4431-424c-8da7-1e3c15a3c91d",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 4",
            "book": "55555555-5555-5555-5555-555555555555"
          },
          {
            "uuid": "8ce51989-ce3e-4ac6-973d-1941d03870b9",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 3",
            "book": "55555555-5555-5555-5555-555555555555"
          }
        ]
      }
    ]
  }
]

Actual behavior (as of v5.6.0)

template is not populated, but comments are

[
  {
    "uuid": "00000000-0000-0000-0000-000000000000",
    "name": "Test Author 1",
    "books": [
      {
        "uuid": "44444444-4444-4444-4444-444444444444",
        "title": "Test Book 1",
        "template": "22222222-2222-2222-2222-222222222222",
        "author": "00000000-0000-0000-0000-000000000000",
        "comments": [
          {
            "uuid": "7d36d725-ab94-4324-b8ce-f2fac30964c2",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 2",
            "book": "44444444-4444-4444-4444-444444444444"
          },
          {
            "uuid": "b35373bb-fb4e-4818-bc58-8ffe691d25c7",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 1",
            "book": "44444444-4444-4444-4444-444444444444"
          }
        ]
      }
    ]
  },
  {
    "uuid": "11111111-1111-1111-1111-111111111111",
    "name": "Test Author 2",
    "books": [
      {
        "uuid": "55555555-5555-5555-5555-555555555555",
        "title": "Test Book 2",
        "template": "33333333-3333-3333-3333-333333333333",
        "author": "11111111-1111-1111-1111-111111111111",
        "comments": [
          {
            "uuid": "9bc6a377-4431-424c-8da7-1e3c15a3c91d",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 4",
            "book": "55555555-5555-5555-5555-555555555555"
          },
          {
            "uuid": "8ce51989-ce3e-4ac6-973d-1941d03870b9",
            "userUuid": "88888888-8888-8888-8888-888888888888",
            "message": "Test comment 3",
            "book": "55555555-5555-5555-5555-555555555555"
          }
        ]
      }
    ]
  }
]

Additional context
This behavior started with v5.6.0. Specifically with bfa4962, which tried to solve #3812.

Versions

Dependency	Version
node	16.15
typescript	4.7.4
mikro-orm	5.6.x
your-driver	PostgreSQL

[B4nan]

Thanks for the repro. The code you mentioned here looks very similar to the test case I've added in that problematic commit, maybe we could just extend it? Looks like it joins two properties on that collection, maybe it's caused by that?

One workaround now would be explicit serialization.

[B4nan]

Hmm looks like the test we have there is reproducing this too, it only asserts the collection is populated, not the nested relations inside it.

[tonyjaimep]

Thank you! 🚀