[rules-users] Object Referencing Error
Esteban Aliverti
esteban.aliverti at gmail.com
Fri Jun 4 07:47:29 EDT 2010
True, I forgot about the objectB field restriction.
2010/6/4 Swindells, Thomas <TSwindells at nds.com>
> In fact in your case you when condition doesn’t make any sense – B will
> never equal the empty string as B isn’t a string.
>
> You probable want the following:
>
> rule “foo”
>
> when
> $a :A(Type == "Prod" , objectB == null)
>
> then
> B bobject = new B();
>
> bobject.setType(“Prod”);
>
> bobject.setId($a.getNumber().getId());
>
> modify($a) {
>
> setObjectB(bobject);
>
> };
>
> end
>
>
>
> This rule only executes when objectB is null, this means you won’t get
> into the loop as once you have created objectB the rule won’t evaluate to
> true again.
>
>
>
> Thomas
>
>
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Esteban Aliverti
> *Sent:* 03 June 2010 23:43
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Object Referencing Error
>
>
>
> Yes, your rule entered in an infinite loop because when every time you
> insert/modify/retract a Fact, rules are reevaluated to check if the
> insertion/modification/retraction generates activations or not. In your
> case, your rule is being reevaluated every time you update your $a object,
> the evaluation ends firing the rule, and this starts an endless loop.
>
> If you only have this behavior with this rule, you can consider using the
> "no-loop" attribute. If your problem is multiple rules being re executed
> (and you don't wont that) you can use "lock-on-active" attribute. Try to
> read the documentation about these attributes for further information.
>
> It is very important for the people new in drools to understand the life
> cycle of a rule.
>
>
>
> Best,
>
> On Thu, Jun 3, 2010 at 7:33 PM, Fnu Mahalakshmi <FMahalakshmi at nyx.com>
> wrote:
>
> Hi,
>
> I tried what you said but program goes into an infinite loop.
> It does not break out of the when loop only.
> I did exactly as you mentioned.
> In the test information I put in a.type = "Prod"
> And a.bObject(new B());
> Any idea whats wrong??
>
> Thanks,
> M
>
> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] On Behalf Of
> rules-users-request at lists.jboss.org
> Sent: Thursday, June 03, 2010 4:52 PM
> To: rules-users at lists.jboss.org
> Subject: rules-users Digest, Vol 43, Issue 15
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> 1. Re: Object Referencing error: (Esteban Aliverti)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 3 Jun 2010 17:51:10 -0300
> From: Esteban Aliverti <esteban.aliverti at gmail.com>
> Subject: Re: [rules-users] Object Referencing error:
> To: Rules Users List <rules-users at lists.jboss.org>
> Message-ID:
> <AANLkTimeZIJ5VfMTBESLFJIWoc_4MEZSXbKMIXAvJRiC at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> You can't modify bobject, becuase it doesn't exist inside the session. You
> just created it a few lines above. Maybe you need an insert() or maybe you
> need the bobject reference from the LHS. Something like this:
>
> *rule* "prod"
>
>
>
> *when*
>
> $a :A(Type == "Prod" , objectB != "")
>
> *then*
>
> B bobject = *new* B();
>
> $a.getObjectB().setType( "Prod" );
>
> $a.getObjectB().setId($a.getNumber().getId());
>
> *update*($a);
>
> * end*
>
> Note that you need to update $a and not B, because A is the inserted Fact
> in
> your session.
>
> Best,
>
>
> 2010/6/3 Fnu Mahalakshmi <FMahalakshmi at nyx.com>
>
> > Hi,
> >
> >
> >
> > I am getting the following error when I try to do complex object
> > referencing in drools:
> >
> > My class:
> >
> > A{
> >
> > String Type;
> >
> > B objectb;
> >
> > //getters and setters for above
> >
> > }
> >
> >
> >
> > My rules:
> >
> >
> >
> > *rule* "prod"
> >
> >
> >
> > *when*
> >
> > $a :A(Type == "Prod" , objectB != "")
> >
> > *then*
> >
> > B bobject = *new* B();
> >
> > bobject.setType( "Prod" );
> >
> > bobject.setId($a.getNumber().getId());
> >
> > *update*(bobject);
> >
> >
> >
> > *end*
> >
> > * *
> >
> > *I want to basically output a file which has updated values of B (type,
> > Id)
> >
> > *
> >
> > * *
> >
> > *Error:*
> >
> > *org.drools.spi.ConsequenceException*: *org.drools.FactException*: Update
> > error: handle not found for object: com.org.Ip at f42ad0. Is it in the
> > working memory?
> >
> > at
> > org.drools.base.DefaultConsequenceExceptionHandler.handleException(*
> > DefaultConsequenceExceptionHandler.java:13*)
> >
> > at org.drools.common.DefaultAgenda.fireActivation(*
> > DefaultAgenda.java:558*)
> >
> > at org.drools.common.DefaultAgenda.fireNextItem(*
> > DefaultAgenda.java:518*)
> >
> > at org.drools.common.AbstractWorkingMemory.fireAllRules(*
> > AbstractWorkingMemory.java:475*)
> >
> > at org.drools.common.AbstractWorkingMemory.fireAllRules(*
> > AbstractWorkingMemory.java:439*)
> >
> > at com.org.DroolsTest.main(*DroolsTest.java:30*)
> >
> > Caused by: *org.drools.FactException*: Update error: handle not found for
> > object: com.org.Ip at f42ad0. Is it in the working memory?
> >
> > at org.drools.base.DefaultKnowledgeHelper.update(*
> > DefaultKnowledgeHelper.java:100*)
> >
> > at com.org.Rule_Prod_Ip_0.consequence(*Rule_Prod_Ip_0.java:10*)
> >
> > at com.org.Rule_Prod_Ip_0ConsequenceInvoker.evaluate(*
> > Rule_Prod_Ip_0ConsequenceInvoker.java:22*)
> >
> > at org.drools.common.DefaultAgenda.fireActivation(*
> > DefaultAgenda.java:554*)
> >
> > ... 4 more
> >
> >
> >
> > Please help! I am very new to drools! Not able to figure out why this
> > error:
> >
> >
> >
> > I am using eclipse and working on Windows machine. Error above was
> > generated on eclipse console.
> >
> >
> >
> > Thank you.
> >
> >
> >
> > M
> >
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