RE: [rules-users] NullPointer in LHS dao calls ..

Since i could not get the earlier code running i tried using eval in LHS side for Dao calls but i keep on getting NullPointerException .. rule "Item should have a valid status" when ItemVo (statusCode : itemStatusCode != null) eval( !itemValidationDao.isValidItemStatus(statusCode) ) then

Status Code is invalid "); end Exception data: org.drools.RuntimeDroolsException: java.lang.NullPointerException at org.drools.rule.EvalCondition.isAllowed(Unknown Source) at

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Source) Can somebody please help .. thanks ________________________________ From: Sanjay Singh - s0singh Sent: Tuesday, April 03, 2007 11:01 AM To: 'Anstis, Michael (M.)'; Rules Users List Subject: RE: Hi. Thanks for getting back to me Mike and Edson and Sorry for the delayed response. I looked at your examples Mike and i felt better as you said that we can make dao calls in LHS .. And Edson suggested not to be afraid of suggesting the same constraint for more than one rule .. i guess i was looking at it more procedural way and dint want any repetition of those conditions as the top level IF block but looks like it won't hurt to mention these constraints in all the rules related to this check ...so i can include this check in all the rules .. hmm .. Here is a quick test i was trying to do for calling the dao in LHS but it fails .. what am i missing .. package com.walmart.itemfile.item.rules import com.walmart.itemfile.item.vo.ItemVo; import com.walmart.itemfile.item.dao.ItemDao; import com.walmart.itemfile.item.dao.ItemValidationDao; import java.lang.String; global com.walmart.itemfile.item.dao.ItemValidationDao itemValidationDao; global com.walmart.itemfile.rules.ValidationErrorMap errors; rule "Item should have a valid status" when ItemVo( statusCode : itemStatusCode != null) ItemVo( statusCode == true ) from itemValidationDao.isValidItemStatus(statusCode) .. my isValidItemStatus method returns a boolean (not collection of codes) and i need to check if thats true than go to the RHS side .. is the line in green even right ... in any case it does not recognize itemValidationDao to begin with in LHS side .. RHS same call works .. then errors.addValidationError("nullItemStatusCode","Item Status Code is null"); System.out.println("Item Base Defaults Called" + itemValidationDao.isValidItemStatus(statusCode)); System.out.println("Item Status Code is null"); end Caused by: org.drools.rule.InvalidRulePackage: unknown:32:28 Unexpected token 'itemValidationDao' thanks for the help guys .. Sanjay ________________________________ From: Anstis, Michael (M.) [mailto:manstis1@ford.com] Sent: Monday, March 26, 2007 8:57 AM To: Rules Users List Cc: Sanjay Singh - s0singh Subject: RE: Hi. Hi Sanjay, To firstly answer your questions (in my opinion): 1. You can't do nested whens in the LHS but you can do nested if / else in the RHS (although you'd fore go the benefits of a RETE-based inference engine; but possible if you've got very few rules and facts...). I believe that there is work to have an "otherwise" statement for rule syntax, how progressed this is and how it will work I don't know - over to Mark and team?!? 2. Yes, take a look at the "from" statement (new for 3.1-M1, see

3. Yes, take a look at rule-flow at

(although I don't know if this is complete if 3.1-M1 - I think it's not). Although I don't think your rules really need rule-flow; you just need to identify and isolate the patterns (IF's) that would cause each "Do Something" to be ran and create a rule for each - this has the benefit of separating each action into a separate rule making maintenance a whole bunch easier). Anyway, I'd try some rules like the following examples (the rest are based upon these):- Rule "Rule 1" when NewItem ( itemStatusCode == null) then //do something end Rule "Rule 2" when $u : User( ) $ni : NewItem ( $isc : itemStatusCode != null ) not Codes ( codes contains $isc ) from valDao.getValidItemStatusCodesForUser($u) then //Do something end Rule "Rule 3" when

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