You may easily specify constraints upon related entities by navigating
associations using createCriteria()
.
List cats = sess.createCriteria(Cat.class) .add( Restrictions.like("name", "F%") ) .createCriteria("kittens") .add( Restrictions.like("name", "F%") ) .list();
note that the second createCriteria()
returns a new
instance of Criteria
, which refers to the elements of
the kittens
collection.
The following, alternate form is useful in certain circumstances.
List cats = sess.createCriteria(Cat.class) .createAlias("kittens", "kt") .createAlias("mate", "mt") .add( Restrictions.eqProperty("kt.name", "mt.name") ) .list();
(createAlias()
does not create a new instance of
Criteria
.)
Note that the kittens collections held by the Cat
instances
returned by the previous two queries are not pre-filtered
by the criteria! If you wish to retrieve just the kittens that match the
criteria, you must use a ResultTransformer
.
List cats = sess.createCriteria(Cat.class) .createCriteria("kittens", "kt") .add( Restrictions.eq("name", "F%") ) .setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP) .list(); Iterator iter = cats.iterator(); while ( iter.hasNext() ) { Map map = (Map) iter.next(); Cat cat = (Cat) map.get(Criteria.ROOT_ALIAS); Cat kitten = (Cat) map.get("kt"); }