[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2978) Using HQL index() on a <index-many-to-many..> key in a <map...> cannot dereference any properties of the key - java.lang.NullPointerException

[James Andrews (JIRA)]

Using HQL index() on a <index-many-to-many..> key in a <map...> cannot dereference any properties of the key - java.lang.NullPointerException
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                 Key: HHH-2978
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2978
             Project: Hibernate3
          Issue Type: Bug
          Components: query-hql
    Affects Versions: 3.2.5
         Environment: Hibernate 3.2.5 GA, MySQL 5.0.27 Community NT, Eclipse 3.1.1, Hibernate Tools 3.2 beta 9
            Reporter: James Andrews


As mentioned in summary, using a mapped POJO as the index of a <map..> relationship, via the <index-many-to-many class="..> approach.

Using a table join, for instance:

select index(depts), depts
from ModificationFixed fixed
left join fixed.departments depts

Will fetch Department instances for each value, but if you instead try to fetch a property of the index:

select index(depts).name, depts
from ModificationFixed fixed
left join fixed.departments depts

then this causes the aforementioned NullPointerException, both in the hibernate tools preview, and in practise when trying to execute the query, with the following stack trace:

Exception in thread "main" java.lang.NullPointerException
	at org.hibernate.hql.ast.HqlSqlWalker.lookupProperty(HqlSqlWalker.java:444)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.propertyRef(HqlSqlBaseWalker.java:1080)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:1881)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:1825)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1394)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:553)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:281)
	at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:229)
	at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:228)
	at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:160)
	at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)
	at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
	at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)
	at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)
	at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)
	at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:115)
	at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)
	at intranet.db.PersistentMySQL.createQueryArray(PersistentMySQL.java:154)
	at intranet.budget.planner.ModificationFixed.main(ModificationFixed.java:165)



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