How to use sleep criteria to return only one element of an object, and not the entire object?

Question

I am trying to get only the id list of the bob object, for example, instead of the bob list. This is fine with an HQL query, but I would know if criteria can be used?

Example:

final StringBuilder hql = new StringBuilder(); hql.append( "select bob.id from " ) .append( bob.class.getName() ).append( " bob " ) .append( "where bob.id > 10"); final Query query = session.createQuery( hql.toString() ); return query.list(); 

Answer 1

I think you could do it with Projections, something like

 Criteria.forClass(bob.class.getName()) .add(Restrictions.gt("id", 10)) .setProjection(Projections.property("id")) ); 

Answer 2

Similarly, you can also:

 Criteria criteria = session.createCriteria(bob.class); criteria.add(Expression.gt("id", 10)); criteria.setProjection(Projections.property("id")); criteria.addOrder(Order.asc("id")); return criteria.list(); 

Answer 3

or setProjection (Projections.id ())

Answer 4

http://www.devarticles.com/c/a/Java/Hibernate-Criteria-Queries-in-Depth/2/

Answer 5

 SessionFactory sessionFactory; Criteria crit=sessionFactory.getCurrentSession().createCriteria(Model.class); crit.setProjection(Projections.property("id")); List result = crit.list(); 

This code will give you a list of identifiers in the model class, for example [1,2,3] . if you want to get a list of arrays, for example, [{"id":1},{"id":2}] , use the following code

 SessionFactory sessionFactory; Criteria crit=sessionFactory.getCurrentSession().createCriteria(Model.class); crit.setProjection(Projections.property("id").as("id")); List result = crit.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP).list(); 

Answer 6

Another option (although the un hibernate-esque bit) is to use "raw" sql, for example:

 List<Long> myList = session.createSQLQuery("select single_column from table_name") .addScalar("single_column", StandardBasicTypes.LONG).list(); 

Answer 7

You can do it like that

  bob bb=null; Criteria criteria = session.createCriteria(bob.class); criteria.add(Restrictions.eq("id",id)); bb = (bob) criteria.uniqueResult(); 

as limitations you can add your condition