[rules-users] Drools crash on simple drl

[Wolfgang Laun]

With a StatelessKnowledgeSession you are supposed to insert all of your facts
you want in Working Memory via the execute method call, and you don't insert
any facts later on.

What you want to do needs a StatefulKnowledgeSession.

-W

On 17/04/2012, Shur, Bob <robert.shur at hp.com> wrote:
> I'm repeating this post because I didn't get an answer last time. Is this
> the wrong place to report a bug? If so, where is the right place? I'm trying
> to understand whether this is really a bug or whether I'm doing something
> wrong.
>
> I have what looks to me like a Drools bug on a simple drl with declared
> classes. I'm using version drools-distribution-5.3.0.Final.
>
> I'm invoking it with this:
>
>         StatelessKnowledgeSession ksession =
> kbase.newStatelessKnowledgeSession();
>         List<Object> facts = new ArrayList<Object>();
>         ksession.execute( facts );
>
> =============================
>
> I get this crash:
>
> 	Exception in thread "main" java.lang.NoClassDefFoundError: com/sample/Cap
> 	at ASMAccessorImpl_129541121334339192620.getValue(Unknown Source)
> 	at
> org.mvel2.optimizers.dynamic.DynamicGetAccessor.getValue(DynamicGetAccessor.java:73)
> 	at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:103)
> 	at
> org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:42)
> 	at org.mvel2.MVEL.executeExpression(MVEL.java:952)
> 	...
>
> ==========================
>
> Here's the drl file:
>
> package com.sample
>
> import com.sample.*;
>
> declare Item
> 	id : int;
> end
>
> declare Priority
> 	name : String;
> 	priority : int;
> end
>
> declare Cap
> 	item : Item;
> 	name : String
> end
>
> rule "split cart into items"
> when
> then
> 	insert(new Item(1));
> 	insert(new Item(2));
> 	insert(new Item(3));
> end
>
> rule "Priorities"
> when
> then
> 	insert(new Priority("A", 3));
> 	insert(new Priority("B", 2));
> 	insert(new Priority("C", 5));
> end
>
> rule "Caps"
> when
> 	$i : Item()
> 	$p : Priority($name : name)
> then
> 	insert(new Cap($i, $name));
> end
>
> rule "test"
> when
> 	$i : Item()
> 	Cap(item.id == $i.id)	
> then
> 	System.out.println("Cap");
> end
>
> ====================
>
> Some observations:
> - If I comment out any of the insert lines, the crash goes away
> - If I change the first field of class Cap to be id:int instead of item:Item
> and make the corresponding changes, the crash goes away
>
>
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