[rules-users] Property Navigation

[Alessandro Lazarotti]

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());
>         }
>
>     }
>
>
>
>
>