Edson

2010/7/16 Meeraj Kunnumpurath <mkunnumpurath@googlemail.com>

Hi Edson,

Just as a matter of interest ... How come the grammar recognizes the null-safe accessors below

CreditTransferTransactionInformation10( eval( !( accountNumbers contains dbtrAcct.?id.?othr.?id ) ) )

and not

CreditTransferTransactionInformation10(dbtrAcct.?id.?othr.?id not memberOf accountNumbers )

Kind regards
Meeraj

On Fri, Jul 16, 2010 at 7:57 PM, Meeraj Kunnumpurath <mkunnumpurath@googlemail.com> wrote:

Thanks Edson.

That worked like a treat

CreditTransferTransactionInformation10( eval( !( accountNumbers contains dbtrAcct.?id.?othr.?id ) ) )

Regards
Meeraj

2010/7/16 Edson Tirelli <tirelli@post.com>

   It does short circuit on "constraints". Not on patterns.

   The problem is your assumption that rules are executed in order. They are not. Check the manual for "Conflict Resolution".

   Also, the LHS of rules are executed at "insert"/"modify" time, so the LHS of both rules will be executed before any of them is fired.

   The shortest syntax for your case is to use an mvel inline eval using the null-safe navigation:

rule X
   dialect "mvel"
when
   ...
    CreditTransferTransactionInformation10( eval( !( accountNumbers contains dbtrAcct.?id.?othr.?id ) ) )

   ...

   Of course, you can do all the null checks in the pattern itself, avoiding the need to use the mvel syntax.

   Edson

2010/7/16 Meeraj Kunnumpurath <mkunnumpurath@googlemail.com>

Thanks Dave.

I think the '||' on rule 1 is getting short-circuited. However, it is the '&&' on rule 2 that is not getting short circuited.

Kind regards
Meeraj

2010/7/16 David Sinclair <dsinclair@chariotsolutions.com>

Drools doesn't use short circuit evaluation, so all of those ORs are going to be evaluated. You may want to consider re-writing your rules or you can use MVEL's null safe navigation for this. dbtrAcct.?id == null, dbtrAcct.?id.?othr == nulll, etc.

dave

2010/7/16 Meeraj Kunnumpurath <mkunnumpurath@googlemail.com>

Hi,

I have the following rules,

global java.util.Set accountNumbers;

rule "rule 1"
when
    $d : Document()
    $c : CreditTransferTransactionInformation (dbtrAcct == null || dbtrAcct.id == null || dbtrAcct.id.othr == null || dbtrAcct.id.othr.id == null) from $d.cstmrCdtTrfInitn.cdtTrfTxInf
    $i : InternalInfo() from $c.internalInfo
then
    $i.setStatus(PaymentStatus.INVALID);
    $i.setErrorCode("PR002");
    $i.setAdditionalInfo("Account number is null");
end

rule "rule 2"
when
    $d : Document()
    $c : CreditTransferTransactionInformation(internalInfo.status != PaymentStatus.INVALID && dbtrAcct.id.othr.id not memberOf accountNumbers) from $d.cstmrCdtTrfInitn.cdtTrfTxInf
    $i : InternalInfo() from $c.internalInfo
then
    $i.setStatus(PaymentStatus.INVALID);
    $i.setErrorCode("PR002");
    $i.setAdditionalInfo("Account number not available in the routing table");
end

My assumption is rule 1 and rule 2 will be executed in the order they appear. Rule 1 checks all the nested attributes are not null and set the status as invalid if any of them is null. Rule 2 uses the and operator and checks the nested attribute is in the collection defined by the global, only if the object is valid. I assume the LHS of rule 2 will be short circuited if the object is invalid. However, if any of the nested property is null I get the following exception from MVEL.

Caused by: [Error: unable to access property (null parent): id]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:861)

Regards
Meeraj

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--
Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com

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--
Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com