[rules-users] Double Handling

[Ade Timi]

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

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