RuleBook first run unexpected result

[typhoon1978]

Hi,

I'm trying to integrate RuleBook in an enterprise project, because it seems to be really interesting.

I'm using version 0.5 and found that first run returns a default value because headRule is not correctly valued in CoRRuleBook.run method. These are the steps I did:

1. First I created a new RuleBook extending CoRRuleBook:

public class AutoEvaluationRuleBook extends CoRRuleBook<MyBean> {

	@Override
	public void defineRules() {
           // here I define all my business rules
	}

}

2. Then I instantiate a new RuleBook:

RuleBook<AutoEvaluationResult> autoEvaluationRuleBook = RuleBookBuilder.create(AutoEvaluationRuleBook.class)
				.withResultType(AutoEvaluationResult.class)
				.withDefaultResult(new AutoEvaluationResult(null, false, false, null))
				.build();

3. Then I create some test cases:

List<NameValueReferableMap<MyBean>> factsList = testCases();

factsList.forEach(x -> {
	count++;
	autoEvaluationRuleBook.run(x);
	autoEvaluationRuleBook.getResult().ifPresent(result -> {
	MyBean ref = result.getValue().getRef();
	System.out.println(String.format("%s. Item: %s, Autoevaluated: %s, Suspect: %s, Reason: %s", count,
		null != ref ? "item" : "NULL", result.getValue().isAutoEvaluated(),
		result.getValue().isSuspect(), null != result.getValue().getReason() ? result.getValue().getReason().name() : "NULL"));
	});
});

In this way, the first run returns an unexpected result because I noticed in the run method inside the CoRRuleBook class the object headRule is not valued.

The original code:

  @Override
  @SuppressWarnings("unchecked")
  public void run(NameValueReferableMap facts) {
   // here an Optional obj wraps the class property _headRule
    Optional<Handler<Rule>> headRule = Optional.ofNullable(_headRule);
    if (!headRule.isPresent()) {
      // if not present (first run), you call defineRules()
      defineRules();
    }
   // here headRule Optional value is still null, is it wanted ?
    headRule.ifPresent(ruleHandler -> {
        ruleHandler.getDelegate().setFacts(facts);
        getResult().ifPresent(result -> ruleHandler.getDelegate().setResult(result));
      });
    headRule.ifPresent(Handler::handleRequest);
  }

In the original code if the headRule is not present, it calls the defineRules, defining the book rules, but after that the method isPresent is called on the Optional<Handler> headRule object which will return false. Is this wanted ?

I modified this code in this way:

@Override
@SuppressWarnings("unchecked")
public void run(NameValueReferableMap facts) {
	Optional<Handler<Rule>> headRule = Optional.ofNullable(_headRule);
	if (!headRule.isPresent()) {
		defineRules();
                // new added line below, rules are defined but object is still not present
		headRule = Optional.ofNullable(_headRule);
	}		
	headRule.ifPresent(ruleHandler -> {
		ruleHandler.getDelegate().setFacts(facts);
		getResult().ifPresent(result -> ruleHandler.getDelegate().setResult(result));
	});
	headRule.ifPresent(Handler::handleRequest);
}

In this way I have all the objects valued correctly (also the first one).

Let me know.

Thanks and best regards,
Alessandro Torrisi.

[Clayton7510]

You are correct. It looks like that is a bug that was probably introduced in v0.5. I just put the fix in 0.5.1-SNAPSHOT. I used the same basic approach as you. The only difference was I checked for null in the first statement.Why? Because another contributor pointed out that it's not considered a good use of Optional just to check isPresent() on an existing variable - not really a big difference tho, IMO.

Thanks for that! I'll update the tests to catch that condition and push it out as a release in the next couple of days. But for now, it's in the current SNAPSHOT release and in the develop branch.

[Clayton7510]

BTW, I can see that you create a RuleBook with the a result type of MyBean here.

public class AutoEvaluationRuleBook extends CoRRuleBook<MyBean> {

	@Override
	public void defineRules() {
           // here I define all my business rules
	}
}

But then you try to instantiate that RuleBook using a different result type of AutoEvaluationResult here.

RuleBook<AutoEvaluationResult> autoEvaluationRuleBook = RuleBookBuilder.create(AutoEvaluationRuleBook.class)
				.withResultType(AutoEvaluationResult.class)
				.withDefaultResult(new AutoEvaluationResult(null, false, false, null))
				.build();

I'm not 100% sure why. But here's an example of what I think you are trying to do. And once again, thanks for finding that bug!

/**
 * Custom RuleBook with a MyBean result type.
 */
public class AutoEvaluationRuleBook extends CoRRuleBook<MyBean> {
  @Override
  public void defineRules() {
    addRule(RuleBuilder.create().withFactType(String.class)
        .withResultType(MyBean.class) //should match the result type of the RuleBook, which is MyBean
        .when(facts -> facts.containsKey("value1"))
        .using("value1")
        .then((facts, result) -> result.getValue().setStrValue1(facts.getOne()))
        .build()
    );
    addRule(RuleBuilder.create().withFactType(String.class)
        .withResultType(MyBean.class) //should match the result type of the RuleBook, which is MyBean
        .when(facts -> facts.containsKey("value2"))
        .using("value2")
        .then((facts, result) -> result.getValue().setStrValue2(facts.getOne()))
        .build()
    );
  }
}

package com.deliveredtechnologies.rulebook.example;

public class MyBean {
  private String strValue1;
  private String strValue2;

  public String getStrValue1() {
    return strValue1;
  }

  public void setStrValue1(String strValue1) {
    this.strValue1 = strValue1;
  }

  public String getStrValue2() {
    return strValue2;
  }

  public void setStrValue2(String strValue2) {
    this.strValue2 = strValue2;
  }
}

public class Application {
  public static void main(String args[]) {
    AutoEvaluationRuleBook ruleBook = new AutoEvaluationRuleBook();
    ruleBook.setDefaultResult(new MyBean());

    NameValueReferableMap factMap = new FactMap();
    factMap.setValue("value1", "First Value");
    factMap.setValue("value2", "Second Value");

    ruleBook.run(factMap);

    ruleBook.getResult().ifPresent(result ->
    {
      MyBean bean = result.getValue();
      System.out.println(bean.getStrValue1());
      System.out.println(bean.getStrValue2());
    });
  }
}

[typhoon1978]

Hi Clayton,

sorry my sample is wrong, because I deleted the real bean name and put at last a generic MyBean.

My real class is declared as follows:

public class AutoEvaluationRuleBook extends CoRRuleBook<AutoEvaluationResult> {
	
	private static final String DATE_PATTERN = "(\\d{4})-(\\d{2})-(\\d{2})";

	private static final int YEAR_GROUP = 1;

	@Override
	public void defineRules() {

		addRule(RuleBuilder.create().withFactType(CalculatedMatching.class).withResultType(AutoEvaluationResult.class)
				.when(personTypeMismatch()).then(unevaluated()).stop().build());
  // and so on...

          }
}

I preferred using the bean approach rather than the map approach.

Thanks and best regards,
Alessandro.

[Clayton7510]

I updated the tests and just pushed 0.5.1 to Maven with this bug fix.