adding excerpt projection to spring data rest repository causes stack overflow error

Question

We are facing StackoverflowError when we enable an except projection on a REST repository. The entity is question has two associations, a @ManyToOne with one Venue entity that has to be included inline for all responses, and a @OneToMany with Trainee entity we always want to hide. The entity (relevant) snippet

@Entity
@EntityListeners(AuditingEntityListener.class)
public class Workshop implements Serializable {

  private static final long serialVersionUID = -5516160437873476233L;

  private Long id;

  // omitted properties

  private Venue venue;

  private Set<Trainee> trainees;

  @Id
  @GeneratedValue
  public Long getId() {
    return id;
  }

  @ManyToOne(fetch = FetchType.EAGER)
  @JoinTable(name = "workshop_venue", joinColumns = { @JoinColumn(name = "workshop_id", referencedColumnName = "id") }, inverseJoinColumns = { @JoinColumn(name = "venue_id", referencedColumnName = "id") })
  public Venue getVenue() {
    return venue;
  }

  @OneToMany
  @JoinTable(name = "workshop_trainees", joinColumns = { @JoinColumn(name = "workshiop_id", referencedColumnName = "id") }, inverseJoinColumns = { @JoinColumn(name = "trainee_id", referencedColumnName = "email") })
  @RestResource(exported = false)
  @JsonIgnore
  public Set<Trainee> getTrainees() {
    return trainees;
  }

  // omitted getters/setters
}

when I add this Projection

@Projection(name = "default", types = { Workshop.class })
public interface InlineVenueProjection {

  String getName();

  Integer getSeatsAvailable();

  WorkshopType getWorkshopType();

  Date getDate();

  Venue getVenue();
}

and enable it in the repository

@RepositoryRestResource(collectionResourceRel = "workshop", path = "workshops", excerptProjection = InlineVenueProjection.class)
public interface WorkshopRepository extends JpaRepository<Workshop, Long> {
// omitted methods
}

I get a stack overflow error in POST requests

org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.StackOverflowError

and further in the stack trace

Caused by: java.lang.StackOverflowError: null
    at java.util.concurrent.locks.ReentrantReadWriteLock$Sync$ThreadLocalHoldCounter.initialValue(ReentrantReadWriteLock.java:286)
    at java.lang.ThreadLocal.setInitialValue(ThreadLocal.java:180)
    at java.lang.ThreadLocal.get(ThreadLocal.java:170)
    at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryReleaseShared(ReentrantReadWriteLock.java:423)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer.releaseShared(AbstractQueuedSynchronizer.java:1341)
    at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.unlock(ReentrantReadWriteLock.java:881)
    at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:169)
    at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:140)
    at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:67)
    at org.springframework.data.mapping.context.PersistentEntities.getPersistentEntity(PersistentEntities.java:63)
    at org.springframework.data.rest.webmvc.mapping.LinkCollectingAssociationHandler.doWithAssociation(LinkCollectingAssociationHandler.java:100)
    at org.springframework.data.mapping.model.BasicPersistentEntity.doWithAssociations(BasicPersistentEntity.java:352)

Nitin Arora · Accepted Answer · 2015-08-08 22:21:07Z

5

The reason you are getting Stack overflow exception is because I guess there is a bidirectional relationship defined between Venue (1-Many) and Workshop (Many-1). You can confirm my assumption.

When you try to serialize venue directly because of the relationship workshop is loaded and it has a reference to venue and hence the endless recursion.

Solution

To resolve this problem, Jackson has @JsonManagedReference and @JsonBackReference.

Workshop Class

public class Workshop implements Serializable {
    ...

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinTable(name = "workshop_venue", joinColumns = { @JoinColumn(name = "workshop_id", referencedColumnName = "id") }, inverseJoinColumns = { @JoinColumn(name = "venue_id", referencedColumnName = "id") })
    @JsonManagedReference
    public Venue getVenue() {
        return venue;
    }

    ...
}

Venue Class

public class Venue implements Serializable {
    ...

    @OneToMany
    @JsonBackReference
    public List<Workshop> getWorkshops() {
        return workshops;
    }

    ...
}

Hope this helps. Let me know if this works.

answered Aug 8, 2015 at 22:21

Nitin Arora

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2 Comments

Anadi Misra Over a year ago

is there a way to get through this without using Bi-Directional relations? I am through the StackoverflowError but now, inlining is even more complicated as it invariably shows Workshops when we fetch Venue, which is not a very good idea given our use case.

Nitin Arora Over a year ago

Try making the @OneToMany relationship lazy. So that when you fetch Venue.Workshops are not fetched. If that does not work, then use @JsonView to control the rendering of fields.

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