6:23 p.m.
I think I've solved this. You have to fire the property change event *AFTER* you
change the underlying property. As long as session.update() is called *AFTER* the value
has changed, things seem to work correctly.
Does this sound like a reasonable solution? I think I saw in the documentation (what
little I could find on this particular subject) that the property event was triggered
before the actual value changed.
Jason Smith
________________________________________
From: rules-users-bounces(a)lists.jboss.org [rules-users-bounces(a)lists.jboss.org] On Behalf
Of Jason Smith [jsmith(a)infotrustgroup.com]
Sent: Friday, November 27, 2009 10:13 AM
To: Rules Users List
Subject: Re: [rules-users] Updates with property change on facts. How???
The Update command appears to be processed in org.drools.process.commands.UpdateCommand.
It's doing the update the same way I am.
Why does this code work when Drools uses it, and it doesn't work for me?
package org.drools.process.command;
import org.drools.reteoo.ReteooWorkingMemory;
import org.drools.runtime.rule.FactHandle;
public class UpdateCommand
implements
Command<Object> {
private FactHandle handle;
private Object object;
public UpdateCommand(FactHandle handle,
Object object) {
this.handle = handle;
this.object = object;
}
public Object execute(ReteooWorkingMemory session) {
session.update( handle,
object );
return null;
}
public String toString() {
return "session.update( " + handle + ", " + object + "
);";
}
}
Jason Smith
________________________________________
From: rules-users-bounces(a)lists.jboss.org [rules-users-bounces(a)lists.jboss.org] On Behalf
Of Jason Smith [jsmith(a)infotrustgroup.com]
Sent: Friday, November 27, 2009 10:04 AM
To: Rules Users List
Subject: Re: [rules-users] Updates with property change on facts. How???
Here is a twist.
If I call "update($fact)" explicitly in the rule, the rule is NOT called twice.
Can someone point me to the code used by "update($fact)"? Maybe I can figure
out what I did wrong to cause the rule to fire incorrectly a second time.
Jason Smith
________________________________________
From: rules-users-bounces(a)lists.jboss.org [rules-users-bounces(a)lists.jboss.org] On Behalf
Of Jason Smith [jsmith(a)infotrustgroup.com]
Sent: Friday, November 27, 2009 9:54 AM
To: Rules Users List
Subject: [rules-users] Updates with property change on facts. How???
I implemented the following listener for my bean and I am calling .update() directly on
the StatefulKnowledgeSession.
QUESTION 1: Is there a better way? The old API supported .insert(fact,boolean). The new
one does not. I am not finding any documentation that explains the new API (version
5.0.1).
QUESTION 2: Why is this calling my rule twice? The rule is getting called twice, and the
second time it's called, the entry conditions are invalid! That is, I changed the
bean in a way that invalidates the WHEN condition. The rule still gets called twice.
How do I even begin to go about troubleshooting this? This same behavior was happening
with Drools 4 and the old API as well.
private class InnerPropertyChangeListener implements PropertyChangeListener
{
private final InternalFactHandle factHandle;
private final Object fact;
private final StatefulKnowledgeSession session;
public InnerPropertyChangeListener(InternalFactHandle factHandle, Object fact,
StatefulKnowledgeSession session)
{
this.factHandle = factHandle;
this.fact = fact;
this.session = session;
}
@Override
public void propertyChange(PropertyChangeEvent evt)
{
System.out.println("****** UPDATING " + evt.getPropertyName() + ":
" +
"\n NEW: " +
StringUtil.indent(BeanUtil.printObject(evt.getNewValue()),16) +
"\n OLD: " +
StringUtil.indent(BeanUtil.printObject(evt.getOldValue()),16));
if((evt.getNewValue() == null && evt.getOldValue() != null) ||
!evt.getNewValue().equals(evt.getOldValue()))
{
session.update(factHandle, fact);
}
}
}
Jason Smith
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