Hi!

I've tried to use hibernate's criteria query API to execute a query that defines a projection using a component property.
The query's root entity is 'Person'. The property used for projection is 'name' of (component) type 'Name'.
Unfortunately, that does not work - instead, the following exception is thrown:

org.hibernate.QueryException: property does not map to a single column: name

Hibernate version:

3.2.3.ga (JBoss 4.2.0.GA)

Code between sessionFactory.openSession() and session.close():

(Note: Class Person has a property 'name' of type 'Name'. The property 'name' is mapped as component using the @embedded annotation on the method 'public Name getName()'.)



Full stack trace of any exception that occurs:

org.hibernate.QueryException: property does not map to a single column: name
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumn(CriteriaQueryTranslator.java:371)
at org.hibernate.criterion.PropertyProjection.toSqlString(PropertyProjection.java:41)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getSelect(CriteriaQueryTranslator.java:310)
at org.hibernate.loader.criteria.CriteriaJoinWalker.<init>(CriteriaJoinWalker.java:71)
at org.hibernate.loader.criteria.CriteriaLoader.<init>(CriteriaLoader.java:67)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1550)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)
at com.dgr.profi.server.offert.HibernateQueryService.findPerson(HibernateQueryService.java:59)

Name and version of the database you are using:

MySQL 5.0.19-nt

OK, it seems there is no proper solution to this problem. So this might be a bug.

In the meantime I've found two possible workarounds to this problem:

1. Do not use projection but query the entire entity. Then the composite property can be accessed programmatically.
   Of course this means that the entire entity is retrieved instead of just the properties I'd like to have.
2. Use a projection list containing every single property of the required component property. An
   Code:
   AliasToBeanResultTransformer
   can be used to transform the discrete properties to a single component bean.
   This solution is fine as long as the result should contain the component property only - as soon as other properties are required too, it does not work any more.

Or is there any mechanism I've not found yet?

Hi,

Using hibernate 3.2.5 GA

I'm having the same problem, I cannot access components through in projections. I think it may have something to do with aliases not being propogated for components.

I tried adding the line:

criteria.createAlias("foo.baz", "baz");

where foo is my class and baz is my component

and then in the projection I have

projectionList.add(Projections.property("baz.bar").as("bar"));

When I execute the query with this amendment, I get 'could not resolve property bar of foo! Without the alias, if I just have foo.baz.bar in my projection, I get the error message, could not find property foo.bar.baz.

Any pointers, hints? or is this something that should be reported as a bug?

Cheers

Sorry, double post. Deleted