IndexOutOfBoundsException when declaring a type in the DRL file

[Myrosia Dzikovska]

I have a type declared in a Java file, and then a type in the DRL file that extends a Java class. What I wanted to do is to have some shared functionality (provided by the Java class), plus different fact types I could match against, and could easily declare in the DRL file. I am getting an unexpected exception and not very informative exception. I don't get this exception if I declare these types in the Java file, so I am guessing that I am doing something wrong/too complex with the declaration. Is there anything that I am missing here?

Java fragment:

    public static class TextOutput extends GenerationOutput {
        private String value;
        private final List<IceComTerm> entities = new ArrayList<>();
       
        public TextOutput(String value) {
            this.value = value;
        }
       
        public TextOutput(String value, List<IceComTerm> entities) {
            this.value = value;
            if (entities != null) {
                this.entities.addAll(entities);
            }
        }
       
        @Override
        public IceComList getBugRepresentation() {
            // ... some code I want all classes to be able to run
        }
    }

Then in the DRL file I have

// Value is declared on text output, but here we add the @key annotation to ensure a constructor is generated
declare FeedbackOutput extends TextOutput
    value: String @key
end

// .... Some rules ....

rule "Input seen"
dialect "mvel"
agenda-group "process input"
salience -1
    when
        $input: DMStudentInput()
    then
        insert(new FeedbackOutput("Oops: got unexpected input " + $input.toString() + ", type: " + $input.getType()))
        retract($input)
end

The goal of this is to have multiple class types I can match against, but shared functionality that they all can use.

If I declare it this way, I get an IndexOutOfBound exception when that rule fires.

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
    at java.lang.String.substring(String.java:1871)
    at org.mvel2.util.ErrorUtil.rewriteIfNeeded(ErrorUtil.java:17)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:952)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:373)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
    at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
    at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
    at org.mvel2.MVELRuntime.execute(MVELRuntime.java:86)
    at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:123)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:119)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:113)
    at org.mvel2.MVEL.executeExpression(MVEL.java:930)
    at org.drools.core.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:107)
    at org.drools.core.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1046)
    at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:152)
    at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:94)
    at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:964)
    at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1234)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1239)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1212)
    at droolsdm.StandaloneDM.userInputLoop(StandaloneDM.java:113)
    at droolsdm.StandaloneDM.main(StandaloneDM.java:134)

If I declare FeedbackOutput in a java file and import it, everything works and I don't get any exceptions. I thought you could re-declare types in a DRL file in order to add annotations. Am I using the type declaration not in the way it was intended?

Thanks

Myrosia

[Davide Sottara]

I agree that the exception is not very informative :)  but to extend a java class with a declare type please make sure you

- import the class (e.g. import com.foo.Text)

- declare it

  declare Text end // needed for compatiblity

- extend it

  declare SubText extends Text .... end

If you miss any of the 3 steps, you should get a compilation error. A KieBase with compilation errors may result in

unpredictable behavior at runtime.

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[Myrosia Dzikovska]

Thanks. This produces different exceptions, though.

If I do the code fragment below, then I get the same index out of bounds exception

import droolsdm.GenerationOutput.TextOutput;

declare TextOutput
end

// Value is declared on text output, but here we add the @key annotation to ensure a constructor is generated

declare QuestionOutput extends TextOutput
    value: String @key
end

....

java.lang.StringIndexOutOfBoundsException: String index out of range: -1

    at java.lang.String.substring(String.java:1871)
    at org.mvel2.util.ErrorUtil.rewriteIfNeeded(ErrorUtil.java:17)

But if I try to mention value on text output, I get  a compilation exception

import droolsdm.GenerationOutput.TextOutput;

declare TextOutput
    value: String
end

// Value is declared on text output, but here we add the @key annotation to ensure a constructor is generated

declare QuestionOutput extends TextOutput
    value: String @key
end

....
New declaration of droolsdm.GenerationOutput$TextOutput can't declaredeclares a different set of fields
existing : {value=private java.lang.String droolsdm.GenerationOutput$TextOutput.value, hashCode=null, class=null, toString=null}
declared : {value=TypeField[ value : [Pattern: id=null; objectType=String] = null ]}

[Davide Sottara]

I see what happens here.. it's indeed a bug, I'll get back to you with more details

Davide

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[dda...@obopay.com]

I am facing the same issue, any further update ?

[Derick Daniel]

Issue is fixed, it was a null pointer exception getting suppressed by drools framework. Thanks.