elements() in simple HQL requires object alias?

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I'm using a simple named query to search for all objects that have a given value-element in a set. It works if I alias the object, but not if I don't. In the code below, query OrganisationsByType1 produces the given exception, OrganisationsByType2 works perfectly.

I've done a quick search through this forum and through JIRA, but I couldn't find anything like this. Does anyone know if this has been fixed, or even if there's a JIRA issue about it that I missed? I am using a fairly old version of hibernate, and I don't expect any fix to be applied to 3.0.5 since there's such an easy workaround, but it should be fixed in future versions.

Hibernate version: 3.0.5

Mapping documents:

Code:

  <class name="OrganisationImpl" table="Organisation">
  ...
    <set name="Types" table="OrganisationTypeLink" lazy="true" cascade="all">
      <key column="OrganisationID"/>
      <element column="OrganisationTypeID" not-null="true"
       type="OrganisationType"/>
    </set>
  </class>

  <query name="OrganisationsByType1">
    from OrganisationImpl
    where :Type in elements(Types)
  </query>

  <query name="OrganisationsByType2">
    from OrganisationImpl o
    where :Type in elements(o.Types)
  </query>

Full stack trace of any exception that occurs:

Code:

java.lang.NullPointerException
   at org.hibernate.hql.ast.MethodNode.handleElements(MethodNode.java:154)
   at org.hibernate.hql.ast.MethodNode.resolveCollectionProperty(MethodNode.java:105)
   at org.hibernate.hql.ast.CollectionFunction.resolve(CollectionFunction.java:22)
   at org.hibernate.hql.ast.HqlSqlWalker.processFunction(HqlSqlWalker.java:538)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.collectionFunction(HqlSqlBaseWalker.java:2273)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.collectionFunctionOrSubselect(HqlSqlBaseWalker.java:3937)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.inRhs(HqlSqlBaseWalker.java:3854)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.comparisonExpr(HqlSqlBaseWalker.java:3517)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1405)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1333)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.whereClause(HqlSqlBaseWalker.java:599)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:404)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:201)
   at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:151)
   at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:189)
   at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:130)
   at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:83)
   at org.hibernate.impl.SessionFactoryImpl.getQuery(SessionFactoryImpl.java:427)
   at org.hibernate.impl.SessionFactoryImpl.checkNamedQueries(SessionFactoryImpl.java:388)
   at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:291)
   at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1005)
        ...

roger_rf · **Posted:** Thu Apr 12, 2007 8:55 pm

I don't really think that's a bug - isn't it mandatory to assign aliases whenever you want to refer to the properties of an instance in more than one place of your query?

http://www.hibernate.org/hib_docs/v3/re ... ryhql.html

I understand that this kind of implicit reference is OK in SQL, but IMHO the alias requirement leads to easier to read, less error-prone code. Cheers,
Roger

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

It is a bug: you can omit the alias, I do it all the time. There's even a few examples in the link you posted, including

Code:

from Cat where name='Fritz'

.

It's not easier to read with the alias, unless the alias is the same as the mapping name (like "from Cat cat where cat.name = 'Fritz'", or whatever). How does "from Cat sdlkjfsdbfh where sdlkjfsdbfh.name" look? Not so great, imo.

This is definitely a bug, and should be resovled. Though it's a very minor bug.

roger_rf · **Posted:** Fri Apr 13, 2007 7:30 am

Hmm, you're correct. I read the third example in section 14.2 and thought there were no exceptions. Most definitely a bug, indeed - fortunately there's an easy workaround. I understand your point about aliases, but you gotta admit that using "sdlkjfsdbfh" for an alias only makes your life harder ;) Cheers,
Roger