[rules-users] Double Handling
Wolfgang Laun
wolfgang.laun at gmail.com
Mon Apr 12 14:11:19 EDT 2010
You are not, by any chance, calling IndividualDecision.calcValues() without
notifying the inference engine? This could mean that the engine still "sees"
the old value (0.0), fires, and the Java access to getLoanToValue() is, of
course, fetched as 92000.0
-W
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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> *T +353 1 685 3001* | VOIP 076 615 1117 | *E adeyinka.timi at nathean.com* |
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> --
> Edson Tirelli
> JBoss Drools Core Development
> JBoss by Red Hat @ www.jboss.com
>
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