[hibernate-dev] Bug in org.hibernate.hql.ast.tree.DotNode#dereferenceEntity, need help assembling test case

[Christopher Smith]

I have run into a bug in 3.6.10.Final that I can replicate and
describe, but I'm not sure how to generate a useful automated test
case (the application I'm working on is using Spring/JPA/Hibernate,
and I don't know how to set up the test sessions and such by hand).
I've traced the bug to DotNode#dereferenceEntity, and I may be able to
debug it further after I garbage-collect my head.

Our use case: We have a class of JPA entity that contains some basic
data.  A handful of these entities have some extended data, and so we
have a separate class with a FK reference back to the basic class
(since most of the entities don't have extended data) and a mapped
Java field from the basic to the extended.  The classes look like this
(plus Roo ITDs):

@Entity public class BasicData {
  @Id private long id;
  @Embedded private String basicInfo;
  @OneToOne(mappedBy="basic") private ExtendedData extended;
}

@Entity public class ExtendedData {
  @Id private long id;
  @Embedded private String extendedInfo
  @OneToOne private BasicData basic;
}

Standard JPA field navigation works fine; we can look up either class
by PK using EntityManager#find and can navigate back and forth.  The
generated DDL is what we expect.

However, the JPQL query "SELECT b from BasicData WHERE b.extended IS
NULL" is compiled incorrectly: The correct SQL is something like
"SELECT * FROM BasicData LEFT JOIN Extended ON BasicData.ID =
Extended.BASIC WHERE Extended.BASIC IS NULL", but Hibernate generates
"SELECT * FROM BasicData WHERE BasicData.ID IS NULL", which of course
returns no records.

When I turn up AST logging, I get this line:
'15:32:26.242 DEBUG org.hibernate.hql.ast.tree.DotNode -
dereferenceShortcut() : property extended in BasicData does not
require a join.'

It appears that the AST is trying to optimize away the join and is
incorrectly believing that it's okay.  I am happy to help create a
test case and to debug the AST analyzer on my end if that will help,
but I'm not sure where to start (since I'm using JPA and not direct
Hibernate).

-- 
Christopher Smith, CCNP, CCDP, MCP, LPIC-1
Sphere Systems