[rules-users] Query in stateless knowledge session returns no results
Hi all,
I'm new to Drools, so please excuse me if I'm asking about the obvious--it's
certainly not obvious to me. The problem is this: I use a stateless knowledge session
where a list of facts is inserted. The rules that fire create new facts, and after all the
rules have fired, I'd like to obtain a list of all the facts (the old and the new).
The best way seemed to use a query. I'm using Drools 5.1 on Linux.
This is part of my .drl file (without the imports):
rule "create badge"
when
Event ( eventType == EventType.SOME_EVENT_TYPE )
not BadgeState ( identifier == "badge" )
then
insert( new BadgeState("badge") );
end
query "all badges"
aBadge : BadgeState()
end
This is the Java code:
StatelessKnowledgeSession ksession =
StatsKnowledgeBase.getKnowledgeBase().newStatelessKnowledgeSession();
// Create a list of share events
ArrayList<Event> events = new ArrayList<Event>();
Date now = new Date();
MobileDevice aDevice = new MobileDevice("uniqueId", "deviceType");
for (int i = 0; i < 5; i++) {
Event anEvent = new Event.Builder(now, aDevice, "aCustomer",
EventType.SOME_EVENT_TYPE).build();
events.add(anEvent);
}
// Create the query for the badges
List<Command> commands = new ArrayList<Command>();
commands.add(CommandFactory.newInsertElements(events));
commands.add(CommandFactory.newQuery("all badges", "all
badges"));
// Feed the events into Drools
KnowledgeRuntimeLogger logger =
KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession);
ExecutionResults results = ksession.execute( CommandFactory.newBatchExecution(commands)
);
NativeQueryResults queryResults = (NativeQueryResults)results.getValue("all
badges");
// At this point, queryResults is empty.
logger.close();
// Get a list of badges
List<BadgeState> badges = new ArrayList<BadgeState>();
for (Iterator<QueryResultsRow> i = queryResults.iterator(); i.hasNext(); ) {
QueryResultsRow result = i.next();
BadgeState obj = (BadgeState)result.get("aBadge");
badges.add(obj);
}
The logger shows me that the BadgeState object is created, but the query returns an empty
list. I've searched the documentation, which suggests that I'm doing it right
(http://drools.herod.net/drools-expert/html/ch03.html#d0e1956, example 3.37), the archives
of this mailinglist, and the web, so far without success.
Clearly, I'm missing something, and I have the nagging feeling that it's something
simple...
Any help is much appreciated!
Best,
Hank