Verified this, in my example if I change the line to Bar.setFoo(null) I get
the following error in my test case:

Exception executing predicate
org.drools.base.mvel.MVELPredicateExpression@6bade9
org.drools.RuntimeDroolsException: Exception executing predicate
org.drools.base.mvel.MVELPredicateExpression@6bade9
	at
org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:216)
	at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:132)
	at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22)
	at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153)
	at org.drools.reteoo.Rete.assertObject(Rete.java:175)
	at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
	at
org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:909)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:881)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:682)
	at mmg.cm.drools.FooBarTest.testProperties(FooBarTest.java:51)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:585)
	at junit.framework.TestCase.runTest(TestCase.java:154)
	at junit.framework.TestCase.runBare(TestCase.java:127)
	at junit.framework.TestResult$1.protect(TestResult.java:106)
	at junit.framework.TestResult.runProtected(TestResult.java:124)
	at junit.framework.TestResult.run(TestResult.java:109)
	at junit.framework.TestCase.run(TestCase.java:118)
	at junit.framework.TestSuite.runTest(TestSuite.java:208)
	at junit.framework.TestSuite.run(TestSuite.java:203)
	at
org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
	at
org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
	at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
	at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
	at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
Caused by: org.mvel.CompileException: unable to resolve property: name
	at
org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:288)
	at
org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:109)
	at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:29)
	at
org.mvel.ast.PropertyASTNode.initializePropertyNode(PropertyASTNode.java:77)
	at
org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:26)
	at
org.mvel.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:21)
	at org.mvel.MVELRuntime.execute(MVELRuntime.java:88)
	at org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
	at org.mvel.MVEL.executeExpression(MVEL.java:235)
	at
org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:36)
	at
org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:210)
	... 28 more
Caused by: org.mvel.PropertyAccessException: unable to resolve property:
name
	at
org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanProperty(ReflectiveAccessorOptimizer.java:382)
	at
org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:257)
	... 38 more



Edson Tirelli-3 wrote:
  

   Really? That is a surprise to me... we need to handle that...

   Maybe you can open a JIRA for us?

   Thanks,
      Edson

2008/5/6 Alessandro Lazarotti <alessandro@siq.com.br>:

    

Thanks Michael, I simulate.. your rule fire with successful.

I discovered the problem. The object in property (like Foo in your
example), when null, it's not throws NullPointerException, but
"org.mvel.PropertyAccessException: unable to resolve property".
With that, I never imagined that the problem was nullPointer, but I
thought about any access visibility (duh!).

[]'s
Alessandro



Michael B. escreveu:

 Okay, I wrote a test case around the following and it works fine so let
      

me
know if this isnt what you are working with...

Foo Class

public class Foo {
       private String m_name;
       public String getName()
   {
       return m_name;            }
       public void setName(String nm)
   {
       m_name = nm;
   }

}


Bar Class

public class Bar {
       private Foo m_foo;
       public Foo getFoo()
   {
       return m_foo;
   }
       public void setFoo(Foo f)
   {
       m_foo = f;
   }
       public String toString()
   {
       return "I have a foo with a name of " + m_foo.getName();
   }

}

DRL Rule

rule "FooBar Rule"

       when
               $bar : Bar( foo.name != "Wrong" )
       then        System.out.println("Test Successful - " +
$bar.toString());

end


Junit Test Case

   public void testProperties()    {
       try
       {
           final Reader source = new InputStreamReader(
FooBarTest.class.getResourceAsStream( "FooBar.drl" ) );
           RuleBase ruleBase = RuleBaseFactory.newRuleBase();
           PackageBuilder builder = new PackageBuilder();
                       builder.addPackageFromDrl(source);
                       if ( builder.hasErrors() ) {
               System.out.println( builder.getErrors().toString() );
               throw new RuntimeException( "Unable to compile
\"FooBar.drl\".");
           }
                       //get the compiled package (which is
serializable)
           final Package pkg = builder.getPackage();

           //add the package to a rulebase (deploy the rule package).
           ruleBase.addPackage( pkg );
           final StatefulSession session =
ruleBase.newStatefulSession();
                       Foo foo = new Foo();
           foo.setName("Test");
           Bar bar = new Bar();
           bar.setFoo(foo);
           session.insert(bar);
                       session.fireAllRules();
   }
       catch (Exception e)
       {
           System.out.println(e.getMessage());
           e.printStackTrace();
           fail(e.getMessage());
       }

   }






        

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-- 
Edson Tirelli
JBoss Drools Core Development
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
JBoss, a division of Red Hat @ www.jboss.com

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