[jboss-jira] [JBoss JIRA] Updated: (JBRULES-515) java NullPointerException when using constraints between fields in same object

[Edson Tirelli (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBRULES-515?page=all ]

Edson Tirelli updated JBRULES-515:
----------------------------------

    Fix Version/s: 3.1-m1
         Assignee: Edson Tirelli  (was: Mark Proctor)

> java NullPointerException when using constraints between fields in same object
> ------------------------------------------------------------------------------
>
>                 Key: JBRULES-515
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-515
>             Project: JBoss Rules
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 3.0.4
>         Environment: Linux
>            Reporter: Sridhar Chandrasekharan
>         Assigned To: Edson Tirelli
>             Fix For: 3.1-m1
>
>
> Consider the following files:-
> 1) Foo.java
> package com.foo;
> public class Foo {
> 	private int a;
> 	private int b;
> 	public Foo(int a, int b) {
> 		super();
> 		this.a = a;
> 		this.b = b;
> 	}
> 	public boolean test()
> 	{
> 		return (a > b);
> 	}
> 	public int getA() {
> 		return a;
> 	}
> 	public int getB() {
> 		return b;
> 	}
> 	
> }
> ******************************************************************************
> 2) FooTest.java
> package com.foo;
> import java.io.InputStreamReader;
> import java.io.*;
>  
> import org.drools.RuleBase;
> import org.drools.RuleBaseFactory;
> import org.drools.WorkingMemory;
> import org.drools.compiler.PackageBuilder;
> import org.drools.rule.Package;
> public class FooTest {
> 	
> 	
> 	/**
> 	 * This is a sample file to launch a rule package from a rule source file.
> 	 */
> 	    public static final void main(String[] args) {
> 	        try {
> 	        	
> 	        	//load up the rulebase
> 	            RuleBase ruleBase = readRule();
> 	            WorkingMemory workingMemory = ruleBase.newWorkingMemory();
> 	            
> 	            //go !
> 	            
> 	            workingMemory.fireAllRules();   
> 	            
> 	            
> 	        } catch (Throwable t) {
> 	            t.printStackTrace();
> 	        }
> 	    }
> 	    /**
> 	     * Please note that this is the "low level" rule assembly API.
> 	     */
> 		private static RuleBase readRule() throws Exception {
> 			//read in the source
> 			Reader source = new InputStreamReader( FooTest.class.getResourceAsStream( "/Foo.drl" ) );
> 			
> 			//optionally read in the DSL (if you are using it).
> 			//Reader dsl = new InputStreamReader( DroolsTest.class.getResourceAsStream( "/mylang.dsl" ) );
> 			//Use package builder to build up a rule package.
> 			//An alternative lower level class called "DrlParser" can also be used...
> 			
> 			PackageBuilder builder = new PackageBuilder();
> 			//this wil parse and compile in one step
> 			//NOTE: There are 2 methods here, the one argument one is for normal DRL.
> 			builder.addPackageFromDrl( source );
> 			//Use the following instead of above if you are using a DSL:
> 			//builder.addPackageFromDrl( source, dsl );
> 			
> 			//get the compiled package (which is serializable)
> 			Package pkg = builder.getPackage();
> 			
> 			//add the package to a rulebase (deploy the rule package).
> 			RuleBase ruleBase = RuleBaseFactory.newRuleBase();
> 			ruleBase.addPackage( pkg );
> 			return ruleBase;
> 		}
> 	
> 	}
> ***************************************************
> 3) Foo.drl
> package com.foo
> rule "Initialization rule"
> 	when
> 		#conditions
> 	then 
> 		assert(new Foo(1,1));
> 		assert(new Foo(2,1));
> 		assert(new Foo(2,3));
> 		assert(new Foo(3,2));
> 		assert(new Foo(3,4));
> 		assert(new Foo(4,3));
> end
> rule "a greater than b"
> 	when
> 		f : Foo(x : a, b < x)
> 		then 
> 		System.out.println("a=" + f.getA() + " b=" +  f.getB() );
> end
> ******************************************
> I get the following error when running the program
> java.lang.NullPointerException
> at org.drools.rule.BoundVariableConstraint.isAllowed(Unknown Source)
> 	at org.drools.common.BetaNodeBinder.isAllowed(Unknown Source)
> 	at org.drools.reteoo.LeftInputAdapterNode.assertObject(Unknown Source)
> 	at org.drools.reteoo.ObjectSource.propagateAssertObject(Unknown Source)
> 	at org.drools.reteoo.ObjectTypeNode.assertObject(Unknown Source)
> 	at org.drools.reteoo.Rete.assertObject(Unknown Source)
> 	at org.drools.reteoo.ReteooRuleBase.assertObject(Unknown Source)
> 	at org.drools.reteoo.ReteooWorkingMemory.doAssertObject(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.assertObject(Unknown Source)
> 	at org.drools.base.DefaultKnowledgeHelper.assertObject(Unknown Source)
> 	at org.drools.base.DefaultKnowledgeHelper.assertObject(Unknown Source)
> 	at com.foo.Rule_Initialization_rule_0.consequence(Rule_Initialization_rule_0.java:7)
> 	at com.foo.Rule_Initialization_rule_0ConsequenceInvoker.evaluate(Rule_Initialization_rule_0ConsequenceInvoker.java:18)
> 	at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
> 	at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
> 	at com.foo.FooTest.main(FooTest.java:27)
> org.drools.spi.ConsequenceException: java.lang.NullPointerException
> 	at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
> 	at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
> 	at com.foo.FooTest.main(FooTest.java:27)
> Caused by: java.lang.NullPointerException
> 	at org.drools.rule.BoundVariableConstraint.isAllowed(Unknown Source)
> 	at org.drools.common.BetaNodeBinder.isAllowed(Unknown Source)
> 	at org.drools.reteoo.LeftInputAdapterNode.assertObject(Unknown Source)
> 	at org.drools.reteoo.ObjectSource.propagateAssertObject(Unknown Source)
> 	at org.drools.reteoo.ObjectTypeNode.assertObject(Unknown Source)
> 	at org.drools.reteoo.Rete.assertObject(Unknown Source)
> 	at org.drools.reteoo.ReteooRuleBase.assertObject(Unknown Source)
> 	at org.drools.reteoo.ReteooWorkingMemory.doAssertObject(Unknown Source)
> 	at org.drools.common.AbstractWorkingMemory.assertObject(Unknown Source)
> 	at org.drools.base.DefaultKnowledgeHelper.assertObject(Unknown Source)
> 	at org.drools.base.DefaultKnowledgeHelper.assertObject(Unknown Source)
> 	at com.foo.Rule_Initialization_rule_0.consequence(Rule_Initialization_rule_0.java:7)
> 	at com.foo.Rule_Initialization_rule_0ConsequenceInvoker.evaluate(Rule_Initialization_rule_0ConsequenceInvoker.java:18)
> 	... 5 more
> If I change the 2nd rule to
> rule "a greater than b"
> 	when
> 		f : Foo()
>                 and eval(f.test())
> 		then 
> 		System.out.println("a=" + f.getA() + " b=" +  f.getB() );
> end
> It works as expected.

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