如何编写 JESS defrule“如果列表中不存在值，则打印出警告”

Question

我是 JESS 的新手，Java 的中级。

我有“cList”作为特殊商品列表（包括“必需”和“区域”商品）， 和“xList”作为所有商品的列表（包括“必需”和“非必需”商品） 我想制定一个规则：如果 'cList' 中不存在状态为 'essential' 的 'xList' 中的 'x'，则打印“缺少基本商品 'x'。”

需要明确的是，我的系统模式与 Jess71p2 中的定价引擎示例相同。

• cList 与 CatalogItems 相同
• xList 与 OrderItems 相同

我从 Java 类中声明 deftemplate。 这是定义模板；

    (import com.aisy.entity.*)
    (deftemplate oldList(declare (from-class oldList)))
    (deftemplate xList  (declare (from-class xList)))
    (deftemplate cList  (declare (from-class cList)))

这是 xList.java

    package com.aisy.entity;
    import java.sql.Timestamp;
    public class xList {
            private Long id_commodity;
            private String commodity;
            private String essentiality;
            private Timestamp update;

        public xList() {
            super();
        }

        public xList(Long id_commodity, String commodity, String essentiality, Timestamp update) {
            super();
            this.id_commodity = id_commodity;
            this.commodity = commodity;
            this.essentiality = essentiality;
            this.update = update;
        }

        public Long getId_commodity() {
            return this.id_commodity;
        }

        public void setId_Commodity(Long id_commodity) {
            this.id_commodity = id_commodity;
        }

        public String getCommodity() {
            return this.commoditty;
        }

        ....getter and setter methods for the rest fields
    }

这是 cList.java；

    public class cList {
        private Long id_commodity;
        private String commodity;
        private String price;
        private Double final_price;

        public cList(Long id_commodity, String commodity, String price, Double final_price) {
            super();
            this.id_commodity = id_commodity;
            this.commodity = commodity;
            this.price = price;
            this.final_price = final_price;
        }

        public cList() {
            super();
        }

            ...common getter and setter methods for all fields

这里是warning.java；

    public class warning {
        private final String description;
        public warning(String aDescription) {
        description = aDescription;
        }

        public String getDescription() {
        return description;
        }
    }

这里是defrule；

    (defrule 
       (xList (commodity ?essential_commodity) (essentiality /essential/))
       (not(cList (commodity ?essential_commodity)))
        => (add ( new warning "Missing essential commodity" ?essential_commodity))
    )

我尝试将一些信息放到 xList 和 cList 的数据库中：

    xList("100000", "PEANUT", "2.45");
    xList("100003", "BREAD", "1.5");

    cList("100000", "PEANUT", "ESSENTIAL");
    cList("100002", "CAKE", "ESSENTIAL");
    cList("100003", "BREAD", "NON ESSENTIAL" );

因此，如果我运行我的规则引擎，结果应该是

   "Missing essential commodity 100002"

但我目前的结果是：

    "Missing essential commodity 100000"
    "Missing essential commodity 100002"

如何解决这个问题？

已编辑：07/22/2016 添加了 xList.java 和 cList.java

Answer 1

当然，确切的语法取决于您要匹配的事实的确切性质。下面的规则是假设有许多“xList”事实，每个事实分别在“commodity”和“essentiality”槽中列出商品的名称及其本质，并且只有一个包含列表的 cList 事实的所有基本商品。空白多字段（“$?”）匹配基本商品前后的任意数量的列表元素。

(defrule 
   (xList (commodity ?essential_commodity) (essentiality essential))
   (not (cList $? ?essential_commodity $?))
    =>
   (assert (warning
       (str-cat "Missing essential commodity" ?essential_commodity))))

Answer 2

欧内斯特快到了：

(defrule 
   (xList (commodity ?essential_commodity) (essentiality essential))
   (not (cList (commodity ?essential_commodity)))
=>
   (assert (warning (description ?essential_commodity)))
)

注意：调用不是列表甚至不包含的类“-List”令人不安（而且它肯定会混淆 Ernest）。类应该被称为somethingCommodity，并且字段名称可能被限制为“id”、“name”等。