Hi Tom,
attached you find my changes fixing the query compiler to generate an
outer join when selecting a relationship field. Here is the
corresponding glassfish issue:
https://glassfish.dev.java.net/issues/show_bug.cgi?id=637
The following query:
SELECT o.customer FROM Order o
should include null in the query result in case there are orders without
a customer. This means the generated SQL needs an outer join between the
order and the customer table.
Some details:
I changed method SelectNode.applyToQuery to set the useOuterJoin flag in
the SelectGenerationContext in case a relationship field is selected.
This code is similar to what method generateExpression already does. The
same change needs to go into ConstructorNode, because a constructor item
might be a relationship access expression. The latter change exposed a
problem in class ReportQueryResult: it runs into NPE in case of a
relationship field with value null. It does not have mapping metadata,
so it tries to get the class instance for the constructor lookup from
the value. I fixed this by retrieving the class instance from the
ClassDescriptor of the corresponding ReportItem. I did not file a
separate issue for NPE, because w/o the relationship fix there are no
null relationship field values in a constructor expression, so the NPE
does not occur.
I think the handling of select expressions in SelectNode needs to be
cleaned up. I propose to do this as part of fixing issue 638.
File JPQL-fix637-060509.jar includes the compiler changes. I also added
two new test cases to a query test class in entity-persistence-tests,
you find them in the other jar JPQL-fix637-test-060509.jar. Please have
a look.
Regards Michael