[OJB-developers] problem with path expressions and extents

[Jakob B. <jbr...@ho...>]

hi all,

we have a general problem when using path expression and extents.
the following test case reads a cd (an extent of article) and then tries to
read the product group using the relationship 'allArticlesInGroup' belonging
to this cd in a second query. the second query cannot find the productgroup
because 'allArticlesInGroup' refers to Article and not to Cd, so the
article-table is used in the join:

SELECT A0.Kategorie_Nr,A0.KategorieName,A0.Beschreibung FROM Kategorien A0
INNER JOIN Artikel A1 ON A0.Kategorie_Nr=A1.Kategorie_Nr WHERE A1.Artikel_Nr
= ?

the query returning the correct result:

SELECT A0.Kategorie_Nr,A0.KategorieName,A0.Beschreibung FROM Cds A0 INNER
JOIN Artikel A1 ON A0.Kategorie_Nr=A1.Kategorie_Nr WHERE A1.Artikel_Nr = ?

i think we need some kind of hints for path expression, so SqlStatement
knows which tables to use.
the hints can be set on Criteria or Query level:

query.useClass("AllProductsInGroup", Cd.class)


Query query;
Criteria crit;
CdArticle cd;
ProductGroup pg;

System.out.println("\nread a single cd");
crit = new Criteria();
crit.addEqualTo("articleId", new Integer(200));
query = new QueryByCriteria(CdArticle.class, crit);
cd = (CdArticle) broker.getObjectByQuery(query);
System.out.println(cd);

System.out.println("\nread product group for cd");
crit = new Criteria();
crit.addEqualTo("allArticlesInGroup.articleId",new
Integer(cd.getArticleId()));
query = new QueryByCriteria(ProductGroup.class, crit);
pg = (ProductGroup) broker.getObjectByQuery(query);
System.out.println(pg);

this kind of query may look a little exotic in the above sample, but it's
the kind of query used in non decomposed m:n relationship. so we definitely
need a solution here.

any help will be appreciated.

jakob