[rules-users] Double Handling

[Edson Tirelli]

   It obviously work for me here... :) as Murphy would predict.

   I added a second rule:

rule "G2 Equity in Asset"
      when
            $d : IndividualDecision(loanToValue < 85.0)
      then
            System.out.println("Lower than 85.0 loanToValue: " +
($d.getLoanToValue()));
end

rule "G2 Equity in Asset - 2"
      when
            $d : IndividualDecision(loanToValue >= 85.0)
      then
            System.out.println("Higher than 85.0 loanToValue: " +
($d.getLoanToValue()));
end

    Result is:

Lower than 85.0 loanToValue: 50.0
Higher than 85.0 loanToValue: 100.0

   I used the drools example code in eclipse as the skeleton for this
application. The snippet is:

            IndividualDecision id1 = new IndividualDecision( 100.0 );
            IndividualDecision id2 = new IndividualDecision( 50.0 );
            ksession.insert( id1 );
            ksession.insert( id2 );
            ksession.fireAllRules();

   No idea what is happening on your environment.

   Edson


2010/4/12 Ade Timi <adeyinka.timi at nathean.com>

>  Thanks guys for your responses. This should be as simple as it gets,
> which adds to my frustration. See the following code below:
>
> *Java classes:*
>
> *Individual* –
>
>             *public* *class* Individual {
>
> *private double assetCost;*
>
> * *
>
> *public* *void* setAssetCost(*double* assetCost) {
>
>             *this*.assetCost = assetCost;
>
>             }
>
>
>
>             *public* *double* getAssetCost() {
>
>                   *return* assetCost;
>
> }
>
> }
>
> *IndividualDecision* –
>
>             *public* *class* IndividualDecision {
>
> *private double loanToValue;*
>
> * *
>
> *public* *void* setLoanToValue(*double* LoanToValue) {
>
>                   *this*.loanToValue = LoanToValue;
>
>             }
>
>             *public* *double* getLoanToValue() {
>
>                   *return* loanToValue;
>
>       }
>
>             *public* *void* calcValues(Individual ind){
>
>             *this*.loanToValue = ind.getAssetCost();
>
>       }
>
> }
>
>
>
> *Rule Resourse – *
>
> *            **import* com...Individual
>
> *import* com...IndividualDecision
>
>
>
> *rule* "G2 Equity in Asset"
>
>       *when*
>
>             $d : IndividualDecision(loanToValue() < 85.0)
>
>       *then*
>
>             System.out.println("loanToValue: " + ($d.getLoanToValue()));
>
> *End*
>
> * *
>
> Hope this helps! Many Thanks again
>  ------------------------------
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Edson Tirelli
> *Sent:* 12 April 2010 15:46
>
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Double Handling
>
>
>
>
>     Ade,
>
>     All these errors you are seeing are totally strange, as this is one of
> the simplest things the rules engine does. Are you able to isolate that into
> a test case that I can run myself to take a look?
>
>     Edson
>
> 2010/4/12 Ade Timi <adeyinka.timi at nathean.com>
>
> This is precisely how I expect it to be expressed. When I express in this
> way I get this error message:
>
>
>
> BuildError: Unable to create Field Extractor for 'loanToValue' of
> '[ClassObjectType class=com.nathean.rules.IndividualDecision]' in rule 'G2
> Equity in Asset'
>
>
>
> even though it is a variable in my IndividualDecision class. I have 3 other
> rule files that have expression in this simple manner and they produce no
> errors and are fine.
>
> But for this, It only lets me use eval or have something like this:
>
> *rule* "G2 Equity in Asset"
>
>       *ruleflow-group* "goods"
>
>       *when*
>
>             $d : IndividualDecision()
>
>             Individual($d.loanToValue < 85.0)
>
>       *then*
>
>             …
>
>             //System.out.println((Double.valueOf("85")).doubleValue());
>
>             System.out.println("loanToValue: " + ($d.getLoanToValue()));
>
> *End*
>
>
>
> I understand that it is pointless having that 2nd line in the when
> section, but it’s the only way it picks up the variables in the
> IndividualDecision class with no errors. I don’t know why I can’t do this
> with this particular rules file. I am using Eclipse. Could there be some
> drools configuration issue with this file?
>
>
>
> -A
>
>
>  ------------------------------
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Wolfgang Laun
> *Sent:* 12 April 2010 14:30
>
>
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Double Handling
>
>
>
> Well, then drop the
>   dialect "mvel"
> and write the pattern as
>    $d : IndividualDecision( loanToVal < 85.0 )
>
> There's no visible need to use mvel.
>
> Or eval: the simplest form for constraints is always best.
>
> -W
>
>
>
> 2010/4/12 Ade Timi <adeyinka.timi at nathean.com>
>
> Many thanks for the response!
>
> Yes it fires when I use 85.0 instead, but it obviously shouldn’t as the
> condition is false. My code now looks like this:
>
>
>
> *rule* "G2 Equity in Asset"
>
>       *ruleflow-group* "goods"
>
>       *dialect* "mvel"
>
>       *when*
>
>             $d : IndividualDecision(*eval*($d.getLoanToValue() < 85.0))
>
>       *then*
>
>             $d.setGoodCount($d.incGoodCount());
>
>             $d.setMessage("0065: G2: Good: Good Equity in Deal");
>
>             //System.out.println((Double.valueOf("85")).doubleValue());
>
>             System.out.println("loanToValue: " + ($d.getLoanToValue()));
>
> *end*
>
>
>
> I still get the print output of 92000.0, which is as I expect but I don’t
> expect the rule to be fired at all. The weird thing is that when I change
> the condition to ‘>’ which is the true condition it never fires! I’m at a
> loss as to why this is happening.
>
>
>
> - Ade
>
>
>  ------------------------------
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Wolfgang Laun
> *Sent:* 11 April 2010 09:11
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Double Handling
>
>
>
> You are comparing a double to a String ("85"). Although MVEL might convert
> strings to numbers, I wouldn't use this without some cogent reason.
>
> Do you have this unexpected firing also when you use a double literal,
> i.e., 85.0 ?
>
> -W
>
> 2010/4/9 Ade Timi <adeyinka.timi at nathean.com>
>
> Hi,
>
>
>
> I am new to Drools. I am having a problem comparing 2 double values. I have
> a Java class with a double attribute called loanToValue. The loanToValue is
> been read from an XML file and the value is 92000.0. Based on this value I
> do not expect this rule to be fired, but for some reason it does. And the
> print statement returns 92000.0. Does anyone know what I’m doing wrong? My
> rule looks as follows:
>
>
>
> *rule* "G2 Equity in Asset"
>
>       *ruleflow-group* "goods"
>
>       *dialect* "mvel"
>
>       *when*
>
>             $d : IndividualDecision()
>
>             Individual(*eval*($d.getLoanToValue() < "85"))
>
>       *then*
>
>             System.out.println("loanToValue: " + ($d.getLoanToValue()));
>
> *end*
>
> * *
>
> Thanks,
>
> Ade
>
>
>
> *Adeyinka Timi* | Technical Supprt | *Nathean Technologies Ltd*
>
> Registered Office 3 Lyncon Court, IDA Science & Technology Park,
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>
> --
>  Edson Tirelli
>  JBoss Drools Core Development
>  JBoss by Red Hat @ www.jboss.com
>
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-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss by Red Hat @ www.jboss.com
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