[rules-users] Query in stateless knowledge session returns no results

[Mark Proctor]

On 31/07/2011 17:25, Heijink, Hank wrote:
> Aha! I missed the line about the dispose. That makes a lot of sense. 
> What I don't understand is why the example 3.37 in the docs would 
> work. If I understand what you're saying, it shouldn't.
It should work, as long as the query is executed as part of the same 
execute batch. We have unit tests f or that too somewhere.

mark
>
> Thanks!
> Hank
>
> Sent from my iPhone
>
> On Jul 30, 2011, at 8:27 AM, "Wolfgang Laun" <wolfgang.laun at gmail.com 
> <mailto:wolfgang.laun at gmail.com>> wrote:
>
>> StatelessKnowledgeSession.execute(...) executes the command(s) and 
>> /finally calls dispose()/ on the session. Use a stateful session or a 
>> global (filled with a low-salience rule) or  -  simply use the 
>> getObjects command.
>> -W
>>
>> On 29 July 2011 22:47, Heijink, Hank <heijink at audible.com 
>> <mailto:heijink at audible.com>> wrote:
>>
>>     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
>>
>>
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>>
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