[rules-users] setting different value in consequence ( RHS part) based on a conditional check

[Wolfgang Laun]

Oh my, aren't we a wee bit too dogmatic? I've certainly been known as being
a stickler to style and best practice and what not, but in this particular
case I'd use a single rule and offload the earth-shaking decision between
'Y' and 'N' into a function:

rule x
when
   samplefact1( $status: status, state == "CA" )
then
   fact0.setField1(  yn( $status)  );
end

Cheers
-W


On 26 January 2012 18:25, Welsh, Armand <AWelsh at statestreet.com> wrote:

> You cannot, under normal circumstances, place conditional login in the
> RHS.  This is by design.  Any conditional logic belongs in the LHS.  If you
> need to perform conditional logic in the RHS, this is usually an indicator
> that they rule is not written correctly.
>
> Now, with that said, there are times when you specifically want to put a
> decision component in the RHS.  I would do this using a function.
>
> In your case, it really would make sense to use two rules, to represent
> your one case, like this:
>
>
> Rule 1
> when
>                samplefact1( status == "active", state == "CA" )
>
> then
>                Response fact0= new Response();
>                fact0.setField1( "Y" );
>                fact0.setName( "something " );
>
>                insert(fact0 );
> end
>
> Rule 2
> when
>                samplefact1( status != "active", state == "CA" )
>
> then
>                Response fact0= new Response();
>                fact0.setField1( "N" );
>                fact0.setName( "something " );
>
>                insert(fact0 );
> end
>
>
> These two rules are mutually exclusive, only one will fire, and you get
> the result you want.  It's really about changing the way you think about
> decision factors.  You can also achieve the same result like this:
>
>
> Rule 1
> when
>                samplefact1(state == "CA" )
>
> then
>                Response fact0= new Response();
>                 fact0.setName( "something " );
>
>                insert(fact0 );
> end
>
>
> Rule 2a
> when
>                samplefact1( status == "active", state == "CA" )
>                $resp : Response ( field1 != "Y")
>
> Then
>        modify( $resp ) { setField1( "Y" )  };end
>
> Rule 2b
> when
>                samplefact1( status != "active", state == "CA" )
>                $resp : Response ( field1 == "Y")
> then
>        modify( $resp ) { setField1( "N" )  };
> end
>
> In this scenario, you are changing from hard data mapping to an event
> oriented rule.  Rule1 creates the basic Response fact, and Rules 2a&2b
> enrich the response fact based on conditions that may arise throughout the
> processing of the rules, independent of the initial creation step.  Just
> whenever you have a response fact that is not Y, set it to Y, and of course
> the inverse rule...  This requires more processing for the rules, but in a
> large rules based system this may be more in-line with what  you really
> want.
>
> Armand
>
> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] On Behalf Of vadlam
> Sent: Thursday, January 26, 2012 8:11 AM
> To: rules-users at lists.jboss.org
> Subject: [rules-users] setting different value in consequence ( RHS part)
> based on a conditional check
>
> Hi,
>
> we have an existing BRL rule in Guvnor whereby we set the value of some
> fields in RHS based on some value checks in the condition part. we have
> created several of these rules already in a previous release.
>
> In the next release, we have new requirements to set the value of an
> existing field  in consequence to be of 2 different values based on a
> specific conditional evaluation. the rest of the rule remains the same.
>
> to clarify,
>
> when
>                samplefact1( status== "active" , state=="CA" )
>
>            then
>
>                Response fact0= new Response();
>                fact0.setField1( "Y" );
>                fact0.setName( "something " );
>
>                insert(fact0 );
>        end
>
> we now have to change this to set Field1 value to Y or N based on some
> updated condition for status field.
>
>  lets say if status=="active" , Field1 has to be Y, but when status=closed,
> then Field1 has to be N
>
> Please keep in mind that the rest of the rule remains the same.
>
> is there a way to set the value of Field1 to be Y or N within the
> consequence part of same rule without having to create another rule .
>
> will the use of functions or variables be of any help in this case?
>
>
>
>
>
>
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/setting-different-value-in-consequence-RHS-part-based-on-a-conditional-check-tp3690826p3690826.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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