Apply Kotlin Value Class unboxing for repository invocations

[mp911de]

When defining a value class as Id type ( MyRepository : Repository<MyEntity, MyValueClass>), calls that pass on Value class instances must apply wrapping/unwrapping according to the rules of how Kotlin expands Value class types.

It would be great to have an interceptor that translates arguments for findById(ID) calls, essentially all methods that accept ID.

See also spring-projects/spring-data-jpa#2840

[w3-3w]

This should also apply to audit types.

@JvmInline
value class Auditor(val str: String)

data class MyEntity(
    @Id val id: Long = 0L,
    val name: String,
    @CreatedBy val createdBy: Auditor = Auditor("UNKNOWN"),
)

@Configuration
@EnableR2dbcAuditing
class AuditConfig {
    @Bean
    fun auditorAware(): ReactiveAuditorAware<Auditor> = ReactiveAuditorAware {
        Auditor("test")
    }
}

In Spring Data 3.2.5, when setting audit parameters, exception throws like

java.lang.ClassCastException: class mypackage.Auditor cannot be cast to class java.lang.String (mypackage.Auditor is in unnamed module of loader 'app'; java.lang.String is in module java.base of loader 'bootstrap')
	at mypackage.MyEntity_Accessor_uf7rrw.setProperty(Unknown Source)
	at org.springframework.data.mapping.model.ClassGeneratingPropertyAccessorFactory$KotlinValueBoxingAdapter.setProperty(ClassGeneratingPropertyAccessorFactory.java:1451)
	at org.springframework.data.mapping.model.InstantiationAwarePropertyAccessor.setProperty(InstantiationAwarePropertyAccessor.java:80)
	at org.springframework.data.mapping.model.SimplePersistentPropertyPathAccessor.setProperty(SimplePersistentPropertyPathAccessor.java:108)
	at org.springframework.data.mapping.model.SimplePersistentPropertyPathAccessor.setProperty(SimplePersistentPropertyPathAccessor.java:127)
	at org.springframework.data.auditing.MappingAuditableBeanWrapperFactory$MappingMetadataAuditableBeanWrapper.lambda$setProperty$0(MappingAuditableBeanWrapperFactory.java:232)
	at java.base/java.lang.Iterable.forEach(Iterable.java:75)
	at org.springframework.data.auditing.MappingAuditableBeanWrapperFactory$MappingMetadataAuditableBeanWrapper.setProperty(MappingAuditableBeanWrapperFactory.java:232)
	at org.springframework.data.auditing.MappingAuditableBeanWrapperFactory$MappingMetadataAuditableBeanWrapper.setLastModifiedBy(MappingAuditableBeanWrapperFactory.java:207)
	at org.springframework.data.auditing.AuditingHandlerSupport.touchAuditor(AuditingHandlerSupport.java:173)
	at org.springframework.data.auditing.AuditingHandlerSupport.lambda$touch$0(AuditingHandlerSupport.java:136)
	at java.base/java.util.Optional.map(Optional.java:260)
	at org.springframework.data.auditing.AuditingHandlerSupport.touch(AuditingHandlerSupport.java:134)
	at org.springframework.data.auditing.AuditingHandlerSupport.markModified(AuditingHandlerSupport.java:127)
	at org.springframework.data.auditing.ReactiveAuditingHandler.lambda$markModified$1(ReactiveAuditingHandler.java:90)
        ...

[mp911de]

@w3-3w I created #2868 out of your comment. While your case doesn't relate to repository invocations per-se, it is still something that works differently between reflective and generated property accessors that we should address.

[larsw]

I've had success with the following workaround for now:

@Repository
interface ContactRepository : JpaRepository<Contact, Contact.Ref> {
    @Query("select count(c) > 0 from Contact c where c._id = :id")
    override fun existsById(id: Contact.Ref): Boolean

    @Query("select c from Contact c where c._id = :id")
    override fun findById(id: Contact.Ref): Optional<Contact>
}

Where Contact.Ref is a Kotlin value class wrapping String.

[utikeev]

Another place for unboxing that should be considered is collections, because value classes are always wrapped when used as generic types.

E.g.:

value class UserId(val value: String)

data class Entity(
  @Id
  val from: UserId,
  val to: UserId,
)

interface EntityRepository : Repository<Entity, UserId> {
  fun findAllByToIn(to: List<UserId>): List<Entity>
}

[c-schicho]

we currently have the same issue. is there any solution work-around for this already?