Well as the question title says, I am trying to make a projection criteria querying only couple of the table attributes.
So I have a Person Table/class and it has about 40 attributes. I want my criteria to get dynamical number of attributes, lets say 10, 11 or 12 (SQL terms select firstname, lastname from person
) and I was doing it like this:
Transaction tx = session.beginTransaction();
Criteria crit = session.createCriteria(Person.class);
crit.setCacheable(true);
ProjectionList projList = Projections.projectionList();
projList.add(Projections.property("id"));
Criterias c = null;
for (int i = 0; i < checked.size(); i++) {
Attribute attr = checked.elementAt(i);
switch (attr) {
case LASTNAME:
projList.add(Projections.property("lastName"));
c = enumMap.get(attr);
if (c.isChanged()) {
String tmp = (String) c.getAnswer();
tmp = tmp.replace('*', '%');
crit.add(Restrictions.like("lastName", tmp));
crit.addOrder(Order.asc("lastName"));
}
case ...THE REST .....
}
crit.setProjection(projList);
retList = crit.list();
tx.commit();
return retList;
and it gives back that the retList
elements are not from the Person.class
:
INFO [AWT-EventQueue-0] (UserGroupManagerApp.java127) - [Ljava.lang.Object;@14b9b80
FATAL [AWT-EventQueue-0] (Login.java78) - java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to usergroupmanager.model.db.Person java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to usergroupmanager.model.db.Person
Please help, for now I am listing all the 40+ attr, and it takes up querying time and I do not like it. I am looking also an alternative solution which will help me solve this. I read about ResultTransformer
but havent found how to use it in my case.
You can use criteria.setResultTransformer()
There's some Transformers provided in Hibernate. If your Person has not any association use this:
criteria.setResultTransformer(Transformers.aliasToBean(Person.class));
But if Person has any association, consider use Seimos at http://github.com/moesio/seimos
A lot of code could be saved if you use it instead Criteria.