Questions about JPQL in Netweaver 7.1

Question

Hello forum.
During the last weeks we tried to migrate a JEE 5 application to SAP Netweaver 7.1.  We encountered quite a few unexpected problems, most of which were related to JPQL queries.
This is the entity structure which we were (and still are) unable to query (simplified pseudo code):
@Entity
class S
   @Id
   @GeneratedValue
   int id;
@Embeddable
class E
   @ManyToOne // unidirectional
   S s;
@Entity
class M
   @Id
   @GeneratedValue
   int id;
   @Embedded
   E e;
What we need is a query for all Ms related to a collection of Ss:
select m from M m where m.e.s.id in (:sids) and ...
The Parameter :sids is set to a HashSet<Integer>.
This seemed to be a few levels too complex for the JPQL interpreter (some error message about s being of unknown type and not having an attribute id ), so we abandoned the Embeddable E and put its members directly into the respective entities, one of them being S.  Is this a shortcoming of SAPs JPQL implementation or did i miss something?
With S being a direct member of M, the JPQL interpreter at least knew about member s being of type S and having an attribute id.  However, it did not accept the parameter being a Collection, but instead expected a single Integer.  I seem to have read here in the forum, that the in operator should be usable with collections, but we never managed to get this working, neither here nor in a simpler case where we needed to fetch all entities S with having an enum attribute in a set of values:
enum Q {... }
@Entity
class S
   Q q;
"select s from S s where s.q in (:qs)"
with :qs set to a Set<Q>.  Changing the parameter to an ArrayList didn't help any further, either.
Does this mean, that collection parameters are unsupported (which would render the in operator rather useless)?
Regards
- Thomas

Answer 1

Hi Thomas,
in JPA 1.0, the IN expression in WHERE clauses does only support subqueries or comma separated lists of literals / input parameters.
Here is the syntax of the JPA (see section 4.6.8 of "JSR 220: Enterprise JavaBeansTM,Version 3.0
Java Persistence API"
in_expression ::=
state_field_path_expression [NOT] IN ( in_item {, in_item}* | subquery)
in_item ::= literal | input_parameter
So you may have to translate your HashSet of Integer in a comma separated list when building the query - not nice but it works.
There is another (strange) IN in JPQL 1.0:  the IN operator that can be used to simplify JOINs on collections, but this IN has nothing to do with WHERE clauses. Maybe you mix the two (see section 4.4.6) example for this:
SELECT DISTINCT o
FROM Order o, IN(o.lineItems) l
WHERE l.product.productType = u2018office_suppliesu2019
Maybe what you try works with JPA 2.0, I am not sure.
Regards,
- Rolf