我需要根据来自后端的数据启用/禁用drl文件中的某些规则。 即启用迪拜规则1,2,3,新加坡启用1,3 所以,我传递drools.getRule()。getName(),如下所示。
rule "Apply 50% discount to VIP customers"
enabled (checkenabled(drools.getRule().getName()))
when
$s : Sale( customer.type == CustomerType.VIP )
then
$s.setDiscount(0.50);
System.out.println("VIP discount applied1" + drools.getRule().getName());
end
我在这方面遇到了错误。
Exception in thread "main" [Error: null pointer: drools.rule.name]
[Near : {... checkenabled(drools.rule.name) ....}]
^
[Line: 1, Column: 14]
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:427)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
at org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:38)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:948)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:373)
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
at org.mvel2.MVELRuntime.execute(MVELRuntime.java:86)
at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:123)
at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:119)
at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:113)
at org.mvel2.MVEL.executeExpression(MVEL.java:930)
at org.drools.core.base.mvel.MVELEnabledExpression.getValue(MVELEnabledExpression.java:92)
at org.drools.core.definitions.rule.impl.RuleImpl.isEffective(RuleImpl.java:384)
at org.drools.core.phreak.RuleExecutor.cancelAndContinue(RuleExecutor.java:326)
at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:142)
at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:94)
at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:964)
at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1234)
at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1239)
at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1212)
at com.emirates.App.testGoodCustomer(App.java:95)
at com.emirates.App.main(App.java:74)
Caused by: java.lang.NullPointerException
at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:393)
... 25 more
答案 0 :(得分:0)
为什么不使用 AgendaFilter ?
非常容易使用,可以在 Java 部分完成,如下所示:
AgendaFilter myFilter = new RuleNameStartsWithAgendaFilter("DUBAI");
mySession.fireAllRules(filter);
myFilter = new RuleNameStartsWithAgendaFilter("SINGAPORE");
mySession.fireAllRules(filter);
AgendaFilter 有多种变体:
我不完全是你所需要的,但它可能是一个提示; - )
答案 1 :(得分:0)
对于"声明性议程来说,这似乎是一个很好的例子。特征。这基于用于阻止规则的规则。这是一个简单的例子:
import org.kie.api.runtime.rule.Match;
rule "Apply 50% discount"
@Eager // required for each rule to be blocked
@Category("Singapore")
when
$s : Sale( article matches ".*PX" ) // anything
then
System.out.println("VIP: " + drools.getRule().getName());
end
rule "CheckBlock"
@Direct @Eager // required for each rule that blocks
when
Location( $country: country )
// $m: Match( Category == "Singapore" )
$m: Match( rule.name == "Apply 50% discount" )
then
kcontext.blockMatch( $m );
end
位置是一个简单的bean。如图所示,阻止规则可以访问"匹配" (神奇地)允许您与元数据或规则名称匹配的对象。当然,评估可以访问位置中的某些方法,以便对规则名称进行更复杂的检查。
请注意,您需要设置一个选项:
KieBaseConfiguration config = ks.newKieBaseConfiguration();
config.setOption( DeclarativeAgendaOption.ENABLED );
或使用kmodule XML(参见文档)。