Question

I have searched but can’t find why this simple code will fail in Drools (core 5.2.1.Final and compiler 5.2.0.Final).

rule "name"
no-loop true
when
    $offer: Offer(properties != null && properties.size() > 0, $properties : properties)
    $invalidProperty: ContextualizedOfferProperty(name == null || "".equals(name)) from $properties
then
...
end

I get the following exception:

java.lang.NullPointerException
    at org.drools.reteoo.FromNode.<init>(FromNode.java:87)
    at org.drools.reteoo.builder.FromBuilder.build(FromBuilder.java:41)
    at org.drools.reteoo.builder.PatternBuilder.attachPattern(PatternBuilder.java:122)
    at org.drools.reteoo.builder.PatternBuilder.build(PatternBuilder.java:76)
    at org.drools.reteoo.builder.GroupElementBuilder$AndBuilder.build(GroupElementBuilder.java:126)
    at org.drools.reteoo.builder.GroupElementBuilder.build(GroupElementBuilder.java:73)
    at org.drools.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:152)
    at org.drools.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:123)
    at org.drools.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:110)
    at org.drools.reteoo.ReteooRuleBase.addRule(ReteooRuleBase.java:419)
    at org.drools.common.AbstractRuleBase.addRule(AbstractRuleBase.java:814)
    at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:555)
    at org.drools.reteoo.ReteooRuleBase.addPackages(ReteooRuleBase.java:436)
    at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:149

If I remove the second binding, it passes correctly. I have tried many different, simple bindings, it always throws if I have two bindings, one referencing the other…

Basically, I want the rule to fire for each ContextualizedOfferProperty that has no name for any Offer having at least one property.

Any idea?

Thanks,

John

Answer 1

It looks like a bug. Have you tried version 5.3.1? It fixes several compilation problems like this.