Almost there - Java 1-1 mapping - but no binding

Question

Hi
I am trying to create a 1-1 mapping for the latest event for a service, and am able to create a new OneToOneMapping in an amendment event for the service descriptor. This generates almost the correct SQL.
OneToOneMapping latestEventMapping = new OneToOneMapping();
latestEventMapping.setAttributeName("latestEvent");
latestEventMapping.setReferenceClass(ServiceHistory.class);
latestEventMapping.dontUseIndirection();
descriptor.addMapping(latestEventMapping);
ExpressionBuilder builder = new ExpressionBuilder(ServiceHistory.class);
Expression latestEventExp = builder.get("serviceId").equal(builder.get("service").get("serviceId"));
ReportQuery subQuery = new ReportQuery(ServiceHistory.class, new ExpressionBuilder());
Expression subQueryExp = subQuery.getExpressionBuilder().get("serviceId").equal(builder.get("serviceId"));
subQueryExp = subQueryExp.and(subQuery.getExpressionBuilder().get("eventDate").greaterThan(builder.get("eventDate")));
subQuery.setSelectionCriteria(subQueryExp);
subQuery.addAttribute("serviceId");
latestEventExp = latestEventExp.and(builder.notExists(subQuery));
latestEventMapping.setSelectionCriteria(latestEventExp);
This creates
SELECT t0.EVENTDATE, t0.EVENTCONT
ENT, t0.EVENTCOMMENTS, t0.EVENTSOURCEID, t0.EVENTTYPEID,
t0.SERVICEID
FROM
     SERVICEHISTORIES t0,
     SERVICES t1
WHERE (((t0.SERVICEID = t1.SERVICEID)
AND NOT EXISTS (
     SELECT t2.SERVICEID FROM SERVICEHISTORIES t2
     WHERE ((t2.SERVICEID = t0.SERVICEID)
     AND (t2.EVENTDATE > t0.EVENTDATE)))
AND (t1.SERVICEID = t0.SERVICEID))
I would expect to see this query generated once for each service object, with a binding for [serviceId = ?] As it is, the query is only called once and all services have the same latest event object reference.
What am I doing wrong? It feels like I am almost there...
James

Answer 1

James
Thanks for the hint - but in your example, where does SERVICE_ID come from? Is this supposed to be a qualified or unqualified database column name
i.e. SERVICES.SERVICEID
or is it a name of the attribute from the class behind the descriptor that owns this mapping? The only place I set the mapping's descriptors class is
descriptor.addMapping(latestEventMapping);
and I am worried that I have not stated that the mapping source class is Service.
At the moment I get the error message
Exception Description: The parameter name [serviceId] in the query's selection criteria does not match any parameter name defined in the query.
Query: ReadObjectQuery(com.surfkitchen.skynet.central.ServiceHistory)
I am confused because I have not defined a query, although I would expect the descriptor's source class (Service) to provide a set of parameters representing the primary key to all of its mappings.
James