Loading and updating rules from a database in Drools 6

Question

How would one go about loading rules from a database table at startup and updating them from the same table in Drools 6.2.0? I\'ve found an example using Drools 5 that I cou

Answer 1

drools-templates has ResultSetGenerator.java which has method compile(resultSet, template) to do the job.

I had data coming over HTTP to be converted to rule. I found a way to do this using ObjectDataCompiler. May be some people might find this useful.

ObjectDataCompiler compiler = new ObjectDataCompiler();
String generatedDRL = compiler.compile(ruleAttributes, new FileInputStream(REGULATION_TEMPLATE_FILE));

where ruleAttributes is

List> ruleAttributes = new ArrayList<>();
Map rule1 = new HashMap<>();
rule1.put("ruleid", "2");
rule1.put("ifcondition", "abc: Abc(xyz.getId() == 2);");
rule1.put("thencondition", "myGlobal.setPqr(200.1D);");
ruleAttributes.add(rule1);

KieBase can then be created like this:

KieServices kieServices = KieServices.Factory.get();

KieHelper kieHelper = new KieHelper();

//multiple such resoures/rules can be added
byte[] b1 = generatedDRL.getBytes();
Resource resource1 = kieServices.getResources().newByteArrayResource(b1);
kieHelper.addResource(resource1, ResourceType.DRL);

KieBase kieBase = kieHelper.build();

Rules can be applied like this:

KieSession kieSession = kieBase.newKieSession();
kieSession.setGlobal("myGlobal", myGlobal);
kieSession.insert(abc);
int numberOfRulesFired = kieSession.fireAllRules();
kieSession.dispose();

Template file looks like this:

template header
ruleid
ifcondition
thencondition

import fk.sp.seldon.msku.MSKU

global com.something.blah.MyGlobal myGlobal

template "tmp1"

rule "@{ruleid}"
  dialect "mvel"
  when
    @{ifcondition}
  then
    @{thencondition};
end
end template