findAll() doesn't load child relations for children extending an abstract class

[Soamid]

I'm using SDN and Neo4j a lot in my project and everything was fine so far, but recently I've encountered strange behaviour. Basically, I created a model consisting of 3 entities connected in the chain: A -rel1-> B -rel2-> C. I added the default Spring Neo4j repository for A entity, filled the database and tried to call aRepository.findAll(). I obtained the result: A -rel1-> B -rel2-> null, C was missing.

It took me several hours to find the root of this problem. Everything was stored correctly in the DB, generated queries looked correct, and the C object was returned in the json results. But somehow it was lost in mapping to the object model. Eventually, I realized it was a problem with the model structure. Class B extends another class, which is abstract. While digging with the debugger I found DefaultNeo4jPersistentEntity#getMostAbstractParent() method which is used to generate key describing data in the mapping process. When an entity has an abstract parent, the relation is resolved as "parent_rel_C" instead of "B_rel_C" (which is the real key in the returned data!).
Moreover, when I load the relationship more directly, by B repository, C is loaded as intended, because an abstract parent is not searched when you process the main entity (this is returned in the aforementioned getMostAbstractParent()).

I think that's the cause of my problem, but I still don't understand why it works that way (and didn't find a mention of it in the documentation). Or maybe it's just a bug. I don't know, but would be grateful for clarification and advice what to do. :)

I've created a small example of the problem:

@Node("A")
public class A {

  @Id
  private final UUID id;

  @Relationship(value = "connectsB", direction = Relationship.Direction.OUTGOING)
  private final B bRelation;

  @PersistenceCreator
  public A(UUID id, B bRelation) {
    this.id = id;
    this.bRelation = bRelation;
  }

  public B getBRelation() {
    return bRelation;
  }
}

public class B extends BParent {

  @Id
  private final UUID id;

  @Relationship(value = "connectsC", direction = Relationship.Direction.OUTGOING)
  private final C cRelation;

  @PersistenceCreator
  public B(UUID id, C cRelation) {
    this.id = id;
    this.cRelation = cRelation;
  }

  public C getCRelation() {
    return cRelation;
  }
}

public class BParent {
}

public interface ARepository extends Neo4jRepository<A, UUID> {
}

  @Test
  void testA() {
    var c = new C(UUID.randomUUID());
    var b = new B(UUID.randomUUID(), c);
    var a = new A(UUID.randomUUID(), b);
    aRepository.save(a);

    List<A> aResults = aRepository.findAll();

    assertEquals(1, aResults.size());
    assertNotNull(aResults.get(0)
        .getBRelation());

   // this assertion fails
    assertNotNull(aResults.get(0)
        .getBRelation()
        .getCRelation());
  }

If you remove the abstract modifier from the BParent class, the test passes.

I'm using Spring Boot 2.7.8 with Neo4j starter (SDN 6.3.7). I wasn't able to check it in the newer versions of the SDN because of some compatibility issues with newer Spring, but at least DefaultNeo4jPersistentEntity code seems unchanged when I checked.

[meistermeier]

Thanks for reporting this and sorry for missing it in the first place.
I am pretty sure it is related to #2819 Basically the same problem here but without the use of projections.
There is a fix mentioned in the issue:
6.3.14-GH-2819-SNAPSHOT
or, if you on a newer version
7.2.0-GH-2819-SNAPSHOT
will close this issue now and try to keep the focus on the linked on for feedback.