[rules-users] using BigDecimal in rules

Marina ppine7 at yahoo.com
Thu Nov 6 09:59:47 EST 2008


Hi,

I'm getting unexpected results when when using BigDecimal objects for matching in rules. 
I'm generating DRL in my code, using freemaker.

I have a RuleEngineNumericFact object which has two attributes:
String propertyName
BigDecimal propertyValue

Below is an example of a rule where I try to match a RuleEngineNumericFact object based on the two attributes:

rule "aaa"
    agenda-group "r1"
    dialect "java"
    when
        (RuleEngineNumericFact( propertyName == "somename" , propertyValue == 10.8 ))
    then
        String ruleId = drools.getRule().getName();
        firedRuleIDs.add(ruleId);
end


Then I create a new RuleEngineNumericFact object and set its propertyValue as following:

String stringValue = "10.8";
BigDecimal propertyValue = new BigDecimal(stringValue, new MathContext(10));

(I also tried to use default precision settings by creating the BigDecimal value as:
BigDecimal propertyValue = new BigDecimal(stringValue);
)

When I insert this fact into the rule engine - the rule does not get fired, so the fact does not match.

One note: if the values are integeres (like, propertyValue == 100) - the rule gets fired. So, it is only the floating point numbers that do not match.

I generate the DRL in my Java code, using freemaker, and I specify the
value that will be used in the rule for matching by calling toString()
method on a BigDecimal object that I get from my business code. The toString() representation ends up to be the "10.8" value (for example).
According to the BigDecimal documentation, marshalling from/to the same string representation shoudl still produce BigDecimal objects that will return TRUE from the equals() method when compared.


any ideas why this is not working here?
How does Drools compare values of objects like BigDecimal?

thanks,
Marina
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