Hibernate: check if object exists

Question

Suppose, objects of type A are stored in DB. Here\'s the way I load specific one from DB using hibernate:

org.hibernate.Session session = ...;
long id         


        

Answer 1

you can use HQL for checking object existence:

public Boolean exists (DTOAny instance) {
    Query query = getSession().             
    createQuery("select 1 from DTOAny t where t.key = :key");
        query.setString("key", instance.getKey() );
    return (query.uniqueResult() != null);
}

Hibernates uniqueResult() method returns null if no data was found. By using HQL you can create more complex query criterium.