Hibernate Criteria and Count Column

Question

I am trying to return an entity with a column that has the count of another table that is a one to many relation. I want to do this using hibernate criteria, not HQL.

select p.*, (select count(*) from child where child.parentid = p.id) as LEVELS
from parent p

Answer 1

If the parent entity also contains a list of children (bi-directional association), you can use criteria to return the count of children as follows:

    Criteria criteria = hibernateSessionHelper.getSessionFactory().getCurrentSession().createCriteria(Parent.class);

    ProjectionList projList = Projections.projectionList();
    projList.add(Projections.countDistinct("children.id"));
    projList.add(Property.forName("field1").group());
    projList.add(Property.forName("field2").group());
    projList.add(Property.forName("field3").group());
    .
    .
    .
    criteria.createAlias("children", "children", CriteriaSpecification.LEFT_JOIN);

    criteria.setProjection(projList);

    List<Object[]> results = crit.list();