Custom RevisionEntity class Metadata null

[csh0034]

I have a problem when using custom entities, in spring data envers 2.5.3

When Create a new DefaultRevisionMetadata or AnnotationRevisionMetadata, metadata is HibernateProxy

EnversRevisionRepositoryImpl

RevisionMetadata<?> createRevisionMetadata() {
  return metadata instanceof DefaultRevisionEntity //
    ? new DefaultRevisionMetadata((DefaultRevisionEntity) metadata, revisionType) //
    : new AnnotationRevisionMetadata<>(metadata, RevisionNumber.class, RevisionTimestamp.class, revisionType);
}

DefaultRevisionMetadata

public final class DefaultRevisionMetadata implements RevisionMetadata<Integer> {
  public Optional<Integer> getRevisionNumber() {
    return Optional.of(entity.getId());
  }
}

AnnotationRevisionMetadata

public class AnnotationRevisionMetadata<N extends Number & Comparable<N>> implements RevisionMetadata<N> {
  private final Lazy<Optional<N>> revisionNumber;

  public AnnotationRevisionMetadata(Object entity, Class<? extends Annotation> revisionNumberAnnotation,
      Class<? extends Annotation> revisionTimeStampAnnotation, RevisionType revisionType) {

    Assert.notNull(entity, "Entity must not be null!");
    Assert.notNull(revisionNumberAnnotation, "Revision number annotation must not be null!");
    Assert.notNull(revisionTimeStampAnnotation, "Revision time stamp annotation must not be null!");
    Assert.notNull(revisionType, "Revision Type must not be null!");

    this.entity = entity;
    this.revisionNumber = detectAnnotation(entity, revisionNumberAnnotation);
    this.revisionDate = detectAnnotation(entity, revisionTimeStampAnnotation);
    this.revisionType = revisionType;
  }
  
  public Optional<N> getRevisionNumber() {
    return revisionNumber.get();
  }

  private static <T> Lazy<Optional<T>> detectAnnotation(Object entity, Class<? extends Annotation> annotationType) {
    
    return Lazy.of(() -> {
      AnnotationDetectionFieldCallback callback = new AnnotationDetectionFieldCallback(annotationType);
      ReflectionUtils.doWithFields(entity.getClass(), callback);
      return Optional.ofNullable(callback.getValue(entity));
    });
  }
}

AnnotationDetectionFieldCallback

public class AnnotationDetectionFieldCallback implements FieldCallback {

  public <T> T getValue(Object source) {

    Assert.notNull(source, "Source object must not be null!");

    Field field = this.field;

    if (field == null) {
      return null;
    }

    return (T) ReflectionUtils.getField(field, source);
  }
}

DefaultRevisionMetadata calls Optional.of(entity.getId());
-> entity is HibernateProxy
-> HibernateProxy.getId();

AnnotationRevisionMetadata calls revisionNumber.get();
-> Optional.ofNullable(callback.getValue(entity))
-> ReflectionUtils.getField(field, source), @RevisionNumber annotated field value

Therefore, when using Custom RevisionEntity, the field value of the HibernateProxy
in org.springframework.data.history.Revision is null. Information about metadata is output only as null or Optional.empty.

if in custom RevisionEntity Adding @Proxy(lazy = false) causes n+1 issues similar issue

any way to solve this problem?

[schauder]

The problematic code is in commons. We'd need either a way to configure the ways these values get accessed or switch to field access. But since the code is in commons we need to evaluate how that might affect other modules.

[schauder]

The plan is to check for Hibernate Proxies and handle them explicitly.