Scala 中的 Drools Expert 输出对象

发布于 2024-12-12 07:12:48 字数 1286 浏览 0 评论 0原文

我是 Scala 和 Drools Expert 的新手，需要一些帮助来从 Drools 会话中获取信息。我已经成功设置了一些由 Drools 规则操作的 Scala 类。现在我想创建一个对象来存储一组输出事实，以便在 Drools 外部进行处理。这就是我所拥有的。

我有一个简单的对象，用于存储数字结果（在规则的 RHS 中生成）以及注释字符串：

class TestResults {
    val results = new MutableList[(Float, String)]()

    def add(cost: Float, comment: String) {
        results += Tuple2(cost, comment)
    }
}

在 DRL 文件中，我有以下内容：

import my.domain.app.TestResults

global TestResults results

rule "always"
    dialect "mvel"
    when
        //
    then
        System.out.println("75 (fixed)")
        results.add(75, "fixed")
end

当我运行包含此内容的代码时，我得到以下错误：

org.drools.runtime.rule.ConsequenceException: rule: always
    at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
...
Caused by: [Error: null pointer or function not found: add]
[Near : {... results.add(75, "fixed"); ....}]
                                                       ^
[Line: 2, Column: 9]
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:997)

在我看来，我在 Scala 中对 TestResults 对象的定义有些愚蠢，以至于 Drools 编译后的 Java 无法完全看到它。也许类型不匹配？我想不通。有什么建议吗？谢谢你！

原文

I'm a novice in both Scala and Drools Expert, and need some help getting information out of a Drools session. I've successfully set up some Scala classes that get manipulated by Drools rules. Now I want to create an object to store a set of output facts for processing outside of Drools. Here's what I've got.

I've got a simple object that stores a numeric result (generated in the RHS of a rule), along with a comment string:

class TestResults {
    val results = new MutableList[(Float, String)]()

    def add(cost: Float, comment: String) {
        results += Tuple2(cost, comment)
    }
}

In the DRL file, I have the following:

import my.domain.app.TestResults

global TestResults results

rule "always"
    dialect "mvel"
    when
        //
    then
        System.out.println("75 (fixed)")
        results.add(75, "fixed")
end

When I run the code that includes this, I get the following error:

org.drools.runtime.rule.ConsequenceException: rule: always
    at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
...
Caused by: [Error: null pointer or function not found: add]
[Near : {... results.add(75, "fixed"); ....}]
                                                       ^
[Line: 2, Column: 9]
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:997)

This looks to me like there's something goofy with my definition of the TestResults object in Scala, such that the Java that Drools compiles down to can't quite see it. Type mismatch, perhaps? I can't figure it out. Any suggestions? Thank you!

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葬花如无物 2024-12-19 07:12:49

您需要在执行会话之前初始化results全局变量。您可以使用以下方法初始化它：

knowledgeSession.setGlobal("results", new TestResults()))

You need to initialize your results global variable before executing your session. You can initialize it using:

knowledgeSession.setGlobal("results", new TestResults()))

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怎言笑 2024-12-19 07:12:49

尝试一下

import my.domain.app.TestResults

global TestResults results

rule "always"
    dialect "mvel"
    when
        //
    then
        System.out.println("75 (fixed)")
        results().add(75.0f, "fixed")
end

我的猜测是类型不对齐并且错误消息很差。（75 是一个 Int，需要一个 Float）

Try

import my.domain.app.TestResults

global TestResults results

rule "always"
    dialect "mvel"
    when
        //
    then
        System.out.println("75 (fixed)")
        results().add(75.0f, "fixed")
end

My guess is that the types don't line up and the error message is poor. (75 is an Int, wants a Float)

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