Stackoverflow-Exception while loading RelationshipEntity in OGM

Question

I have the following classes:

@NodeEntity
public class Item{
  //...
}

@RelationshipEntity(type = "HAS")
public class HasRelation{
  //...
  @StartNode
  private User user;

  @EndNode
  private Item item;
}

@NodeEntity
public class User{
  //...
  @Relationship(type="HAS")
  private Set<HasRelation> has;
}

So now I have a User Sven with ID 1 having an Item Hammer in the Database and want to load it. When I call the OGM session.load(User.class, 1) I always get an Stackoverflow-Exception, because the User hold a Relationship, holding the User, holding a relationship, and so on. This feels like the wrong way to use OGM for me and I don't want to restrict the Depth by which I load to 0. However the OGM specification tells me, that there is no other way, since the RelationshipEntity needs a Start- and EndNode and has to be referenced in one of those. So I don't see a way to prevent this Exception other than resticting the Loading-Depth to 0. Is there a better way?

Answer 1

You are exposing the data as JSON. The converter also needs to traverse the 'object tree' and this causes the stackoverflow.

The solution is simple: You are defining an outgoing relationship in the User class so this object does not need to be visited again when the jackson lib hits the relationship.

@RelationshipEntity(type = "LIKES")
public class LikedBook {

@Id
@GeneratedValue
private Long id;

private String how;

@StartNode
@JsonIgnore // <- "do not go back"
private User user;

@EndNode
private Book book;