problem with derived property in criteria query

randov · **Joined:** Wed Mar 16, 2005 10:13 am **Posts:** 3

Hibernate version: 3.0RC1

I have a persistent class 'A' what has a component 'comp'. One of the component's properties is derived (let's call it 'derived') by specifying SQL in 'formula' attribute in mapping document.

This construction works fine if I load object of type A and access its component's derived property. E.g.

Code:

A a = (A) session.load(A.class, key);
System.out.prinln(a.getComp().getDerived());

But the problems appear when I want to set restriction on this derived property in criteria query. E.g.

Code:

Criteria c = session.createCriteria(A.class);
c.add(
  Restrictions.eq("comp.derived", value)
);
c.list();

When executing criteria query, I get NullPointerException:

Code:

java.lang.NullPointerException
   at org.hibernate.persister.entity.AbstractPropertyMapping.toColumns(AbstractPropertyMapping.java:68)
   at org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:33)
   at org.hibernate.persister.entity.BasicEntityPersister.toColumns(BasicEntityPersister.java:1104)
   at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumns(CriteriaQueryTranslator.java:402)
   at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumnsUsingProjection(CriteriaQueryTranslator.java:368)
   at org.hibernate.criterion.SimpleExpression.toSqlString(SimpleExpression.java:42)
   at org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:313)
   at org.hibernate.loader.criteria.CriteriaLoader.<init>(CriteriaLoader.java:92)
   at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1228)
   at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:299)
        ...

Is anybody run to the same problem? Or what I am missing here?

Thanks,
Rando

drj · **Posted:** Wed Mar 16, 2005 1:17 pm

If your property is a purely derived property (i.e. not mapped by hibernate) then you can't query the database againt it.

randov · **Joined:** Wed Mar 16, 2005 10:13 am **Posts:** 3

This is probably not a case. The property A.comp.derived has Hibernate mapping, but not directly to the database column, but via formula (SQL expression calling stored function):

Code:

<property name="derived"
    formula="( IS_VALID(fromDate, untilDate) )"/>

regards,
Rando

drj · **Posted:** Thu Mar 17, 2005 12:01 pm

Ok - so it is mapped as a formula. It should work. What happens when you query on the column using HQL?

randov · **Joined:** Wed Mar 16, 2005 10:13 am **Posts:** 3

The same problem is also when quering via HQL like:

Code:

Query q = session.createQuery("from A a where a.comp.derived=?");
q.setParameter(0, value);
q.list();

It seems, that the problem is present when the derived column is inside a component.

In method org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns() for 'formula'-mapped columns a template value is searched from formulaTemplatesByPropertyPath map. But for component properties this map does not contain entries (e.g. for key 'comp.derived' in my case) and that's why NPE is thrown.

regards,
Rando

max · **Posted:** Thu Mar 17, 2005 5:32 pm

put it in jira