[rules-users] Update vs insert

[Quinn, Dan]

I agree that update is the proper route to take. This question is more
about my understanding of drools. My theory was insert would work as
long as my hashcode and equals methods are overriden correctly, which I
believe I have done. Since that didn't work, I thought there was
something fundemental about drools that I didn't understand. 

My first assumption was something with shadow facts was causing my
problems. I am using Drools 5 and another user, Micheal, mentioned
Drools 5 does not use shadow facts. If that's the case I am further
confused as to why it didn't work.

Below is the code I am using. It's a pretty simple use case. In the
code, I pull the fact out of working memory before I run the query, and
look at the class name. Its been updated properly(i.e it equals Math),
but the query still doesn't return the Person fact. Is there something
about the query that relies on a property change listener firing before
it will re-analyze working memory to get results.

        String name = "Dan";
        Person daniel = new Person(name, "M", 29);
        daniel.setLikesMath(true);
        
        Person Chris = new Person("Chris", "M", 34);
        Chris.setLikesMath(true);
        
        Person Debbie = new Person("Deb", "F", 34);
        Debbie.setLikesMath(false);
        
        FactHandle danielHandle = DroolsUtil.insertOrUpdate(daniel);
        DroolsUtil.insertOrUpdate(Chris);
        DroolsUtil.insertOrUpdate(Debbie);
        
        DroolsUtil.fireAllRules();
        
        Person extractedDaniel =
(Person)DroolsUtil.getObject(danielHandle);
        
        // This line prints out Math
        System.out.println("Dans class: " +
extractedDaniel.getClassName());
        
        List<Person> students = 
 
(List<Person>)DroolsUtil.getQueryResults("getPeopleForClass", "Math");
        DroolsUtil.fireAllRules();
        
        System.out.println("Number of students: " + students.size());

Thanks again for any help.

Daniel Quinn
Fedex - Custom Critical
Software Specialist I
234.310.4090(x2586)

-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Ingomar Otter
Sent: Thursday, September 11, 2008 6:53 AM
To: Rules Users List
Subject: Re: [rules-users] Update vs insert

Ehm, I would think that unless person implements a
PropertyChangeListener, you need to tell the engine about the change of
the slot.
Update would be the proper way AFAIK.

In this case, I don't see why one would  want to insert an object into
WM - as it is already in WM.
I think the exact result of the insert depends on whether you have
implemented equals/hashCode properly.
But again, in that example I understand that you want to change the
property of an object you have matched  in the LHS.
The way to do this is using update().

-- Ingomar

Am 11.09.2008 um 12:39 schrieb Shyam, Pallav (MSCIBARRA):

> Very strange. The facts are passed into the WM by-reference.  
> Therefore the query should work after calling the
> person.setClassName("Math") on the fact. And this should work without 
> calling the insert or update.
>
> This leaves me guessing that the query does not work on the facts 
> directly, instead they work on shadow facts.
>
>
>
>
> ________________________________
>
> From: rules-users-bounces at lists.jboss.org
> To: Rules Users List
> Sent: Thu Sep 11 04:41:37 2008
> Subject: [rules-users] Update vs insert
>
>
> Hello,
>
>   What is the difference between calling insert and update in a rule 
> file? When I use insert my queries don't work, but if I use update 
> they seem to. I don't mind using update, but I would like to 
> understand the difference between the two. Here is my rule file.
>
>    rule "Add person to math class"
>    no-loop
>        when
>            person : Person(likesMath == true)
>        then
>            person.setClassName("Math");
>            insert(person);
>    end
>
>   I also have a query:
>
>   query getPeopleForClass(String _className)
>      Person(className == _className)
>   end
>
>   When I add two facts to working memory, where the likesMath 
> attribute is true, then run my query I get zero results back. When I 
> change the rule, "Add person to math class", to use update(person) 
> instead of insert(person) two students are returned.
>
>  Any help would be appreciated.
>
> Thanks,
> Dan
>
>
> Daniel Quinn
> Fedex - Custom Critical
> Software Specialist I
> 234.310.4090(x2586)
>
> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org 
> [mailto:rules-users-bounces at lists.jboss.org
>  <mailto:rules-users-bounces at lists.jboss.org> ] On Behalf Of 
> thomaskukofka at web.de
>
> Sent: Wednesday, September 10, 2008 2:27 PM
> To: rules-users at lists.jboss.org
> Subject: [rules-users] Re: looping problem
>
> Hello,
>
> thanks that works. I just forgot to set the focus in the init rule..
>
> Regards
> Thomas
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users 
> <https://lists.jboss.org/mailman/listinfo/rules-users
> >
> --------------------------------------------------------
>
> NOTICE: If received in error, please destroy and notify sender.  
> Sender does not intend to waive confidentiality or privilege. Use of 
> this email is prohibited when received in error.
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users


_______________________________________________
rules-users mailing list
rules-users at lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users