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@lists.jboss.org [mailto:rules-users-bounces@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@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 2^nd 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@lists.jboss.org [mailto:rules-users-bounces@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@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@lists.jboss.org [mailto:rules-users-bounces@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@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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T +353 1 685 3001 | VOIP 076 615 1117 | E adeyinka.timi@nathean.com | www.nathean.com

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JBoss Drools Core Development
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