@JoinColumns breaks on Hibernate Reactive

[LarsSven]

Describe the bug

If you write an entity like the following:

@Entity
class ExampleParentEntity(
    @field:ManyToOne(fetch = FetchType.EAGER)
    @field:JoinColumns(
        value = [
            JoinColumn(name = "id", referencedColumnName = "id"),
            JoinColumn(name = "revision", referencedColumnName = "revision")
        ]
    )
    var child: ExampleEntity = ExampleEntity(),

    @Id
    var parentId: UUID = UUID.randomUUID(),
)

And then try to retrieve it from the database when using Hibernate Reactive, your program crashes with a rather vague exception (and no usable stacktrace:
class org.hibernate.sql.results.graph.embeddable.internal.EmbeddableInitializerImpl cannot be cast to class org.hibernate.reactive.sql.results.graph.ReactiveInitializer (org.hibernate.sql.results.graph.embeddable.internal.EmbeddableInitializerImpl and org.hibernate.reactive.sql.results.graph.ReactiveInitializer are in unnamed module of loader io.quarkus.bootstrap.classloading.QuarkusClassLoader @2fc0cc3)

As far as I understand, this happens because Hibernate Reactive does not support JoinColumns, which then makes it fall back on the default Hibernate ORM implementation, which breaks because you can't run non-reactive code in a reactive context.

I think the problem is twofold. Ideally, this would be fixed such that it works, but also the exception in its current form is incredibly hard to debug. This took us a really long time to figure out, reproduce, and isolate from the rest of the entity code to figure out this was causing the issue.

I made a minimal reproduction of the issue, which you can pull from here: https://gitlab.com/l.s.andringa1/hibernate-reactive-reproducer. There is a unit test in that project that breaks with the explained issue.

Expected behavior

When running repository.find(), the entity should simply be retrieved from the database without throwing exceptions.

Actual behavior

Hibernate throws an exception around using non-reactive code in a reactive environment

How to Reproduce?

Reproducer: https://gitlab.com/l.s.andringa1/hibernate-reactive-reproducer

Steps:

1. Clone repository
2. Run EntityTest unit test
3. Observe failure

Output of uname -a or ver

6.11.0-13-generic #14-Ubuntu SMP PREEMPT_DYNAMIC Sat Nov 30 23:51:51 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

Output of java -version

openjdk version "21.0.5" 2024-10-15

Quarkus version or git rev

3.17.4

Build tool (ie. output of mvnw --version or gradlew --version)

Gradle 8.9

Additional information

No response

[quarkus-bot]

/cc @DavideD (hibernate-reactive), @gavinking (hibernate-reactive), @geoand (kotlin)

[DavideD]

THanks for the reproducer, I will have a look

[LarsSven]

For reference, this is our production repository where we originally found the issue, https://gitlab.com/rug-digitallab/products/themis/themis-core/-/tree/ls/172-persistence?ref_type=heads

Here we get a slightly different error, as it tries to cast a different class:
class org.hibernate.sql.results.graph.entity.internal.EntityInitializerImpl cannot be cast to class org.hibernate.reactive.sql.results.graph.ReactiveInitializer (org.hibernate.sql.results.graph.entity.internal.EntityInitializerImpl and org.hibernate.reactive.sql.results.graph.ReactiveInitializer are in unnamed module of loader io.quarkus.bootstrap.classloading.QuarkusClassLoader @5b0dbfb)

But yeah this repository is of course a lot more cluttered, so best to refer to the minimised reporducer

[LarsSven]

@DavideD do you happen to know if this bug is resolvable in the near future? An important feature is currently blocked on this so we are thinking about whether it's reasonable to wait for this or move away from hibernate-reactive / redo our entity design to work around the bug.

[DavideD]

I didn’t have the time to check this, but I solved a similar issue not too long ago. So, it shouldn't be too hard to fix it, once I've verified the issue (finger crossed). This happens when embedded ids are involved. Because of the holidays, I don’t think I will be able to check this until January though Lars ***@***.***> schrieb am Do. 26. Dez. 2024 um 17:05:

…

@DavideD <https://github.com/DavideD> do you happen to know if this bug is resolvable in the near future? An important feature is currently blocked on this so we are thinking about whether it's reasonable to wait for this or move away from hibernate-reactive / redo our entity design to work around the bug. — Reply to this email directly, view it on GitHub <#45188 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEIQ5OQLHSKGROSP24TMKT2HQSNJAVCNFSM6AAAAABT2ZG65KVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKNRSHEYTMMZWHE> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[LarsSven]

@DavideD thanks a lot for taking your time for this. Have you had a chance to look at it?
Also is it sufficient to have an issue at the Quarkus project, or should an issue also be open at the hibernate-reactive repo?

[DavideD]

I will have a look at this this week

[DavideD]

Hi, we figured out the problem. It's the same as this one: hibernate/hibernate-reactive#2060

It will be fixed in the next release