[rules-users] Nested properties and memberOf

[David Sinclair]

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 at 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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