Store rules in a relational Database: deprecated class KnowledgeBase

[tommaso borgato]

Hi,

I use Drools version 5 in one of my projects, a very important one actually.

I am upgrading to Drools 6 and class KnowledgeBase is deprecated.

I store my rules in a database table:

create table dhmatevo.t_matevo_rules (

    rule_name varchar2(100) not null,

    rule_content clob,

    active number(1,0) default 1 not null

)

I load the rules from the table with the following code:

List<String> rules = MyRepository.getRulesFromDatabase();

KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
Iterator<String> rulesIterator = rules.iterator();
while (rulesIterator.hasNext()){
        kbuilder.add(ResourceFactory.newReaderResource(new StringReader(rulesIterator.next())), ResourceType.DRL);
}

KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
kbase.addKnowledgePackages( kbuilder.getKnowledgePackages() );
if ( kbuilder.hasErrors() ) {
    Iterator<KnowledgeBuilderError> errors = kbuilder.getErrors().iterator();
    while (errors.hasNext()) {
        KnowledgeBuilderError error = errors.next();
        logger.error("Errore compilazione regole Drools : {}", error.getMessage());
    }
} else {
    this.knowledgeBase = kbase;
}

Which is the best way to load rules from my table in version 6 ?

Thank you all in advance for your support,

Tommaso Borgato

[Davide Sottara]

The closest and easiest way is to use the KieHelper class. I don't have the pointers to the examples right now, but others may help. The interface may be intuitive enough anyway.
Let us know if you have more questions

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[tommaso borgato]

Thank you!

This code worked for me:

<String> rules = DataHubRepository.getRulesFromDatabase(dataSourceDhsathub);

KieHelper helper = new KieHelper();

Iterator<String> rulesIterator = rules.iterator();
while (rulesIterator.hasNext()){

    Resource resource = ResourceFactory.newReaderResource(new StringReader(rulesIterator.next()));
    resource.setResourceType(ResourceType.DRL);
    resource.setSourcePath("myrule");
    resource.setTargetPath("myrule");
    helper.addResource(resource);
}
KieBase kbase = helper.build();
this.kieBase = kbase;