Question

I got an Entity 1 -> SubEntity n One-To-Many-relation.

I just would like to check, if this is the most efficient way to search for an Entity, including a specified SubEntity in its “One-To-Many-Collection”. It works, but do I have to join fetch the SubEntities or is there a more lightweight solution if I don’t need all SubEntities to be loaded? (FetchMode = Lazy)

public Entity getEntityBySubEntity(SubEntity subEntity) { 
     List<Entity> result = (List<Entity>)getHibernateTemplate.findByNamedParam(
         "From Entity as e left join fetch e.subEntities as sub where sub.id = :id","id",subEntity.getId()); 
     if (!result.isEmpty()) { 
          return result.get(0);
     } else {
          throw new NoResultException();
     }
 }

(by the way, there should always be just one result…)

thx in adv,

cav

Answer 1

Your query is fine, but needlessly fetches the subEntities. Just remove the fetch keyword. And since the sub-entity can’t be null to satisfy the condition, an inner join is OK:

select e from Entity e inner join e.subEntities sub where sub.id = :id