I'm trying to check if property is null, but the rule is never fired : Sample : rule "Cancel" when $action : CancelProductBookingDetail( created == null ) then end (created is of type java.util.Date) Any help is appreciated. Hendy -- View this message in context: http://drools.46999.n3.nabble.com/How-to-check-if-a-property-IS-null-tp40... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

Thank you. Here's a very simple use case : https://github.com/ceefour/droolsnull Running this on Drools 5.4.0 will output: 00:29:34.122 [main] INFO c.h.droolsnull.BookingService - getNullQty() called! 00:29:34.125 [main] INFO c.h.droolsnull.BookingService - getFilledQty() called! 00:29:34.139 [main] INFO c.hendyirawan.droolsnull.DroolsNull - Notify has filled sentTime: Thu Aug 16 00:29:34 WIT 2012 00:29:34.139 [main] INFO c.hendyirawan.droolsnull.DroolsNull - Notify has NULL sentTime 00:29:34.140 [main] INFO c.hendyirawan.droolsnull.DroolsNull - You've got a filled booking with qty 5.0 00:29:34.140 [main] INFO c.hendyirawan.droolsnull.DroolsNull - You've got a NULL booking 00:29:34.140 [main] INFO c.hendyirawan.droolsnull.DroolsNull - BookingService can return filled qty: 10.0 Expected is one more: BookingService can return NULL qty BookingService.getNullQty() is called by the Drools rule but then ignored. How to capture this? The rules : package com.hendyirawan.droolsnull dialect "mvel" import org.slf4j.*; import com.hendyirawan.droolsnull.*; global Logger log; global BookingService bookingService; rule "Booking data with not null qty exists" when $booking : Booking( $qty : qty != null ) then log.info("You've got a filled booking with qty {}", {$qty}); end rule "Booking data with null qty exists" when $booking : Booking( qty == null ) then log.info("You've got a NULL booking"); end rule "BookingService can return null qty" when Double( this == null ) from bookingService.getNullQty() then log.info("BookingService can return NULL qty"); end rule "BookingService can return filled qty" when $qty : Double() from bookingService.getFilledQty() then log.info("BookingService can return filled qty: {}", {$qty}); end rule "Notify has null sentTime" when $notify : Notify( sentTime == null ) then log.info("Notify has NULL sentTime"); end rule "Notify has filled sentTime" when $notify : Notify( $sentTime : sentTime != null ) then log.info("Notify has filled sentTime: {}", {$sentTime}); end The rule that isn't working : rule "BookingService can return null qty" when Double( this == null ) from bookingService.getNullQty() then log.info("BookingService can return NULL qty"); end Thank you. Hendy (I also once had a criteria like " $notify : Notify( sentTime == null ) " not working but can't reproduce it again yet. if I can find it I'll post again) -- View this message in context: http://drools.46999.n3.nabble.com/How-to-check-if-a-property-IS-null-tp40... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

Thank you. "this == null" is weird indeed in Java, but I honestly don't know how to express this expression in Drools DSL. A more realistic rule would be: when $product : Product( ) Double( this == null ) from bookingService.getQty( $product ) So what I want to do is detect when a method call returns null. The method call can contain parameters but it can be a simple method like before. How to do this? Thank you. Hendy -- View this message in context: http://drools.46999.n3.nabble.com/How-to-check-if-a-property-IS-null-tp40... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

Thank you. "this == null" is weird indeed in Java, but I honestly don't know how to express this expression in Drools DSL. A more realistic rule would be: when $product : Product( ) Double( this == null ) from bookingService.getQty( $product ) So what I want to do is detect when a method call returns null. The method call can contain parameters but it can be a simple method like before. How to do this? Thank you. Hendy -- View this message in context: http://drools.46999.n3.nabble.com/How-to-check-if-a-property-IS-null-tp40... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users