Confirmed, the NPE is a bug.. The use case was not covered. A tentative fix is here, we'll discuss it next week
https://issues.jboss.org/browse/DROOLS-564 https://github.com/sotty/drools/commit/9db38d098e67560839b36661bdf24a5f5cdae1df Davide On 07/23/2014 10:56 PM, Borris wrote: > I want to pass strings around between rules and queries to control their > actions and provide control values. I know I can just use "literals" but > I know from past experience that that leads to small typos not being > detected (either at compile time or run time) and leads to nasty subtle > errors down the line. > > For rules, you can over come this with a bunch of public static final > String in a class (I call mine Consts) - and then any spelling mistakes > become compile time issues as you are matching against a > variable/constant name and if you spell this right then you know you get > the right control string. > > But does anyone have a technique that works with queries? I know lots of > the docn talks about queries being things you can invoke from Java. But > I use queries in my rules (they have a private stack and support > recursion that rules don't quite do in the same way). Does anyone have a > clever technique they've used in the past? > > Thanks > > Borris > > > On 22/07/2014 17:16, Davide Sottara wrote: >> The case may not be supported, but even then, it should be reported as >> a compilation error, not as a NPE >> I'll investigate and report back later >> Thanks >> Davide >> >> On 07/22/2014 05:48 PM, Borris wrote: >>> I was experimenting with ways of avoiding having to put literal strings >>> into my rules (it is very fragile and bugs can be silent for a long >>> time). I tried declaring a global and then tried supplying it to a >>> query. This generates a backtrace during the newKieSession. A simple >>> example to provoke the problem: >>> >>> >>> KieServices ks = KieServices.Factory.get(); >>> KieContainer kContainer = ks.getKieClasspathContainer(); >>> KieSession kSession = >>> kContainer.newKieSession("ksession-rules"); >>> >>> kSession.setGlobal("AString", "Hello World"); >>> >>> kSession.fireAllRules(); >>> >>> >>> >>> package com.sample >>> >>> global java.lang.String AString; >>> >>> declare Thing >>> name: String @key >>> end >>> >>> rule init >>> when >>> then >>> insert( new Thing( AString ) ); >>> end >>> >>> query test(String $in) >>> Thing( $in; ) >>> end >>> >>> rule spot >>> when >>> test( "Hello World"; ) >>> Thing( "Hello World"; ) >>> test( AString; ) >>> Thing( AString; ) >>> then >>> System.out.println("found msg\n"); >>> end >>> >>> >>> java.lang.NullPointerException >>> at >>> org.drools.core.rule.LogicTransformer.processElement(LogicTransformer.java:243) >>> at >>> org.drools.core.rule.LogicTransformer.processElement(LogicTransformer.java:263) >>> at >>> org.drools.core.rule.LogicTransformer.fixClonedDeclarations(LogicTransformer.java:134) >>> at >>> org.drools.core.rule.LogicTransformer.transform(LogicTransformer.java:99) >>> at >>> org.drools.core.definitions.rule.impl.RuleImpl.getTransformedLhs(RuleImpl.java:560) >>> at >>> org.drools.core.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:105) >>> at >>> org.drools.core.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:100) >>> at >>> org.drools.core.impl.KnowledgeBaseImpl.addRule(KnowledgeBaseImpl.java:1455) >>> at >>> org.drools.core.impl.KnowledgeBaseImpl.addRule(KnowledgeBaseImpl.java:1435) >>> at >>> org.drools.core.impl.KnowledgeBaseImpl.addPackages(KnowledgeBaseImpl.java:838) >>> at >>> org.drools.core.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:266) >>> at >>> org.drools.compiler.kie.builder.impl.KieContainerImpl.createKieBase(KieContainerImpl.java:412) >>> at >>> org.drools.compiler.kie.builder.impl.KieContainerImpl.getKieBase(KieContainerImpl.java:346) >>> at >>> org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:498) >>> at >>> org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:469) >>> at com.sample.DroolsTest.main(DroolsTest.java:17) >>> >>> >>> The 3rd action in the spot rule causes the null exception during >>> initialise, if it is present. Comment out just that line and no >>> exceptions happen and behaviour is as expected. >>> >>> Are globals permitted in the way I am trying to use them, as a parameter >>> to a query? >>> >>> Borris >>> >>> >>> >>> >>> _______________________________________________ >>> rules-users mailing list >>> rules-users@lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/rules-users >>> >> _______________________________________________ >> rules-users mailing list >> rules-users@lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users > _______________________________________________ > rules-users mailing list > rules-users@lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > _______________________________________________ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
