Question

我试图在Drools中使用accumulate函数从日期列表（Java 8）中找到最小日期。

这是我的规则：

rule "Print minimum Service Date from Bill Lines"
when
  accumulate ( 
    $lineItem : LineLevelData($dateOfService : dateOfService) , 
    $epochDay : min($dateOfService.toEpochDay())  
  )
  $minServiceDate : LocalDate() from LocalDate.ofEpochDay($epochDay)
then
  System.err.println("Min. Service Date used in rules calculation : " + $minServiceDate);
end

这是我得到的例外：

Unable to Analyse Expression LocalDate.ofEpochDay($epochDay):
[Error: unable to resolve method using strict-mode: java.time.LocalDate.ofEpochDay(java.lang.Comparable)]
[Near : {... LocalDate.ofEpochDay($epochDay) ....}]
                       ^ : [Rule name='Print minimum Service Date from Bill Lines']

显然，我在这里缺少一些基础知识。有人可以帮我解决这个问题吗？

Drools版本：7.5.0

POJO：

public class LineLevelData{

LocalDate dateofService;
}

更新

rule "Print minimum Service Date from Bill Lines"

    when
                    accumulate ( $lineItem : LineLevelData (  $dateOfService : dateOfService   ) , 
                                                              $epochDay : min($dateOfService.toEpochDay())  )
                    $epochLong : Number (longValue  > 0 ) from $epochDay
                    $minServiceDate : LocalDate(  ) from LocalDate.ofEpochDay($epochLong)
            then

            System.err.println("Min. Service Date used in rules calculation : " + $minServiceDate);

end

将演员表添加到Long后，epoch将转换为Local date。如果它可以帮助某人寻找这个，那么添加它。

Answer 1

我想问题是Drools没有保留min函数返回的类型，而是将其视为Comparable而不是long。

有三种方法可以解决这个问题：

Create your own accumulate function处理LocalDate
使用accumulate with inline code
使用下面的解决方法强制Drools cast Comparable返回LocalDate。

解决方法：

rule "Print minimum Service Date from Bill Lines"
when
  $c: Comparable() from accumulate ( 
    LineLevelData($dateOfService : dateOfService) , 
    min($dateOfService)  
  )
  $minServiceDate: LocalDate() from $c
then
 System.err.println("Min. Service Date used in rules calculation : " + 
   $minServiceDate);
end

希望它有所帮助，

Drools - 查找最小Java 8本地日期

1 个答案: