[rules-users] eval call from java code

[rogelio_sevilla1]

Good day everyone:

Sorry if this is a too basic question.

I'm having a recurrent problem on my rules and I still don't know how to
really solve it, I searched here at the forum but I'm not so sure that the
solutions proposed would work for my use case. 

I have to call many different methods on the LHS of some of my rules so I
insert a global 'utils' object and I make my calls within eval() blocks,
like this:

$myObj1: ClassX (eval(globalUtil.reSupplyNeeded(amount)  ))


 Everything works fine for now.  I wrapped all my util methods within try
catch blocks to avoid screwing up my stateful session (in my use case, is
CRITICAL to keep the session alive). So, if an exception is thrown, I return
false or true depending on the method.


My main problem is with evals where I do comparisons like this one:

eval($myObj1.doSomething()==$myObj2.doSomething())

I have many of these and some times I get an annoying NPE. I know I could
add   !=null  comparisons but my rules would grow considerably. eval is
extremely useful so I was wondering if I can call it from my utility class,
something like this:


On my Drl file:

rule "eval called from here and utility class"
when
$someObj1 : ClassX()
$someObj2 : ClassY()
$myObj : Class1( eval(  
globalUtil.doEval($someObj1.doSomething()==$someObj2.doSomething()  ) ) )
then
...bla bla bla
end


On my Utility Class

public boolean doEval(ClassIDontKnow argument){

try{
//I don't know if this even exists, just asking if it's possible
return Drools.eval(argument);
}
catch(Exception e){
logger.error("Something bad happened!!");
return false;
}

}



Is something like this even possible?? , if not, other approach that you
would recommend me??


Thanks a lot in advance :-)










 





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