Hi,
You have to "let go" of the need to explicitly iterate collections within rules.
You wouldn't normally think about iterating all records yourself in a database when performing a SQL statement like this:-
select sum(ch.claimAmount) as total from claim c, claimHistory ch where c.claimId = ch.fk_claimId;
So your rules can work in much the same way:-
global Long total;
when
$c : Claim()
$h : ClaimHistory( claimId == $c.claimId )
then
total = total + $h.getClaimAmount();
end
This rule will activate for every combination of Claim and ClaimHistory (where claim ID's match) in Working Memory.
Relating this to your example you should be able to do the following:-
when
$c : DURClaim()
$ch : ClaimsHistory()
$h : DURClaim() from $ch.getHistory()
then
//Do some computation involving $c and $h
end
This will match on every combination of DURClaim and ClaimsHistory's DURClaim in Working Memory. AFAIK Drools does not support Java's generics in pattern matching so I have shown use of "ClaimsHistory" rather than using "List" to prevent matching on any other List you may have in WM. Obviously you'd need to insert "claims" into WM not "historyClaims".
If ClaimsHistory.getHistory returned a List of objects of a class other than DURClaim you could have used the option to explode the list first using a higher salience rule (as in my earlier email) however, in your case, it'd be difficult to prevent matching between different instances of DURClaim that represent different "inClaim" objects if the rule simply contained two "DURClaim" patterns.
With kind regards,
Mike
On 5 May 2011 13:03, sdinoo
<sdinoo@gmail.com> wrote:
Hi Michael
Thank you for helping me out - but I need some more help
Pardon my ignorance, but I am still not clear how this can be done
I am looking for something in the language that will allow me to iterate
through the entire List/Vector object by object and then access each object
instances values like Object.getClaimAmount
Here is my calling program
public static final void main(String[] args) {
DURUtils rc = new DURUtils();
//Load the claims from CSV into History
ClaimsHistory claims = new ClaimsHistory();
List<DurClaim> historyClaims = claims.getHistory();
System.out.println("List Size = " + historyClaims.size());
//Create a New Incoming object
IncomingClaim ic = new IncomingClaim();
DurClaim inClaim = ic.getIncomingClaim();
try {
// load up the knowledge base
KnowledgeBase kbase = readKnowledgeBase();
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
KnowledgeRuntimeLogger logger =
KnowledgeRuntimeLoggerFactory.newFileLogger(ksession, "test");
// start a new process instance
ksession.insert(inClaim);
ksession.insert(historyClaims);
ksession.startProcess("com.drughistory");
ksession.fireAllRules();
logger.close();
} catch (Throwable t) {
t.printStackTrace();
}
}
private static KnowledgeBase readKnowledgeBase() throws Exception {
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(ResourceFactory.newClassPathResource("trials/ClaimProcessing.bpmn"),
ResourceType.BPMN2);
//kbuilder.add(ResourceFactory.newClassPathResource("DurClaimRules.drl"),
ResourceType.DRL);
kbuilder.add(ResourceFactory.newClassPathResource("trials/History.drl"),
ResourceType.DRL);
return kbuilder.newKnowledgeBase();
}
All I want to do is some computation using the
incomingClaim with a List of the historyClaims
The incoming claim and the historyclaims are of the same model claim called
DURClaim
Again, this may be a very elemental question but I thought there would be an
easier way of doing this as I would like to keep the iteration processing in
the rule rather than outside in a Java Class
--
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