Easy-Rules 规则引擎，不能同时触发多个事实

Question

我正在尝试将简单规则的商店教程 (shop) 扩展到多个 facts 上的运行。在规则中编写条件时，我们使用 "fact name" 调用函数，如下所示，

condition: "people.isAdult() == false"

因为people只是facts中一个对象实例的名字，像上面那样定义条件是不行的。我如何定义条件以使其遍历多个 facts.

我想要实现的是在规则引擎的一次火灾中评估多个事实的规则。

当将一组具有相同事实名称的事实提供给规则引擎时，仅评估最后提供的一个。但是，当为每个事实分配不同的名称时，我无法为每个事实分配相同的条件。

下面是代码。假设 Person class 对所有成员都有基本的 get/set 功能。

Rules.yml:

---
name: "regex"
description: "Check if regex pattern matches"
priority: 1
condition: "people.getPayload().matches(\".*12.*34$\") == true"
actions:
 - "System.out.println(\"There is a match\");"
---
name: "age"
description: "Check if person's age is > 18 and marks the person as adult"
priority: 2
condition: "people.age > 18"
actions:
  - "people.setAdult(true);"
---
name: "alkol"
description: "children are not allowed to buy alcohol"
priority: 3
condition: "people.isAdult() == false"
actions:
  - "System.out.println(\"Shop: Sorry, you are not allowed to buy portakal\");"

主线：

//create a person instance (fact)   
            Person [] PeopleArray = new Person [100];
            Person [] KidsArray = new Person [300];

        // initialize arrays
            for(int i = 0; i < PeopleArray.length ; i++)
            {
               PeopleArray[i] = new Person("TOM"+i,23);
               PeopleArray[i].setPayload(dummystring);
            }
            for(int i = 0; i < KidsArray.length ; i++)
            {
                KidsArray[i] = new Person("EMRE"+i,13);
                KidsArray[i].setPayload(dummystring);
            }


        Facts facts = new Facts();

        // create a rule set
        Rules rules = MVELRuleFactory.createRulesFrom(new FileReader("rules.yml"));

        RulesEngine rulesEngine = new DefaultRulesEngine();

        System.out.println("Tom: Hi! can I have some Vodka please?");

      //put the facts
        for(int i = 0; i < PeopleArray.length ; i++)
            facts.put("people", PeopleArray[i]);
        long start = System.currentTimeMillis();
        for(int i = 0; i < KidsArray.length ; i++)
            facts.put("people", KidsArray[i]);

        rulesEngine.fire(rules, facts);

Answer 1

一个Facts对象本质上是一个hashmap。所以按照设计，你不能把两个事实放在同一个键上。

我在您的示例中看到 people 事实是一个数组。现在如何在 mvel 表达式中处理数组是另一回事了。老实说，我能给出的最佳答案是查看 MVEL 文档：https://github.com/imona/tutorial/wiki/MVEL-Guide#arrays

What I want to achieve is evaluate the rules on multiple facts in one fire of the rule engine.

我不确定这是否可以通过简单的规则实现。我认为你可以：

要么平面图你的事实
或者根据不同的事实多次调用 fire

希望这对您有所帮助。

Answer 2

Fact其实就是一个Map

Map<String, Object> facts = new HashMap<>()       // from source code

如果您需要添加多个事实，然后使用它们同时触发规则，您可以使用 List 来完成。可以创建一个 List<Object> 并将此 List 添加到 Facts.

规则Class:

@Rule(name = "Hello World rule", description = "Always say hello world")
public class HelloWorldRule {

    @Condition
    public boolean when() {
        return true;
    }

    @Action
    public void then(@Fact("facts") List<Object> arr) throws Exception {
        for (Object i : arr) {
            System.out.print(i + ", ");
        }
    }

}

启动器Class:

public class Launcher {

    public static void main(String[] args) {

        // create facts
        Facts facts = new Facts();
        List<Object> arr = new ArrayList<>();
        arr.add("hello");
        arr.add(5);
        facts.put("facts", arr);

        // create rules
        Rules rules = new Rules();
        rules.register(new HelloWorldRule());

        // create a rules engine and fire rules on known facts
        RulesEngine rulesEngine = new DefaultRulesEngine();
        rulesEngine.fire(rules, facts);

    }
}

请记住，如果您拥有相同类型的所有对象而不是 Object，这将非常有用，就像在本例中 Person.

Easy-Rules 规则引擎，不能同时触发多个事实

Easy-Rules Rule engine, cannot fire on multiple facts at once

java

rule-engine

mvel