财产访问问题

Question

我尝试使用这个规则：

rule "conformSyncConstraint"
    when
    $syn_con : SyncConstraint(
        $left_stp_period  : leftSTP.period,
        $right_stp_period : rightSTP.period)
    eval( ($left_stp_period.dayOfWeek == $right_stp_period.dayOfWeek &&
        $left_stp_period.dayOrder == $right_stp_period.dayOrder) == false) 
    then
    insertLogical(new IntConstraintOccurrence("conformSyncConstraint", 
        ConstraintType.NEGATIVE_HARD,
        1,
                $syn_con));
end

但我面临着这个错误，它似乎是一个黑匣子：

Rule Compilation error : [Rule name='conformSyncConstraint']
    in/co/technovia/timetabler/domain/Rule_conformSyncConstraint_4401252830cd4ee7bc49416ead3da86c.java (8:1459) : The field Period.dayOfWeek is not visible
    in/co/technovia/timetabler/domain/Rule_conformSyncConstraint_4401252830cd4ee7bc49416ead3da86c.java (8:1490) : The field Period.dayOfWeek is not visible

    at org.drools.planner.config.solver.SolverConfig.buildRuleBase(SolverConfig.java:238)
    at org.drools.planner.config.solver.SolverConfig.buildSolver(SolverConfig.java:170)
    at org.drools.planner.config.XmlSolverConfigurer.buildSolver(XmlSolverConfigurer.java:103)
    at in.co.technovia.timetabler.TimeTableApp.createSolver(TimeTableApp.java:61)
    at in.co.technovia.timetabler.TimeTableApp.main(TimeTableApp.java:45)

这里出了什么问题？

Answer 1

任何时候使用eval，都会回退到所使用的方言。在您的情况下，您使用的是java方言，因此必须使用java语法编写表达式：.getDayOfWeek（）而不是.dayOfWeek.

如果不使用evals，或者将方言切换为mvel，则可以使用简化的语法。

例如：

when
    $syn_con : SyncConstraint(
        leftSTP.period.dayOfWeek != rightSTP.period.dayOfWeek ||
        leftSTP.period.dayOrder != rightSTP.period.dayOrder
    )
then