[rules-users] NullPointerException with Wrapper objects

[Shannon Lal]

Shabbir,
Do you still need to code section for this? If so, can you show me how you
are loading this into the Working Memory(i.e. the Java code you use prior to
executing the rules).

Shannon

2009/5/14 Wolfgang Laun <wolfgang.laun at gmail.com>

> All right, let's hope that "business user" is up to write the rules, even
> without null checks ;-)
> Seriously now: are they up to handling monetary units represented as
> floating point numbers? A recent thread has emphasized the problems arising
> from tests such as floatVal <= floatConst, and I've been preaching about
> possible inconsistencies due to the inherent nature of FP arithmetic, even
> for doing sums. BigDecimal is one solution, but I guess your BUs will go
> ballistic if you tell them about the consequences...
>
> But here's my last proposal for circumnavigating the NPE issue:
>
> At the point of fact insertion, wrap all "dangerous" bean objects into a
> container fact with a single field and insert the container. Write rules
> matching the container, testing the wrapped object for field == null and
> whatever; if so, change and log; and now insert the wrapped object as a fact
> proper. (If necessary, you could even write a single rule for all fact
> types, using inspection to determine all dangerous fields.)
>
> -W
>
>
> 2009/5/14 Shabbir Dhari <sdhari at hotmail.com>
>
>>  Thanks to all.
>>
>> The problem we have is that rules will be code by business user. As a
>> developer I don’t mind putting null check on every rule. But for business
>> user its unacceptable for checking null for the same attribute in around 50
>> rules.
>>
>> Shannon, can you please elaborate more about your solution or if possible
>> post some simple code?**
>> > Date: Wed, 13 May 2009 08:28:53 -0700
>> > From: greg_barton at yahoo.com
>> > Subject: RE: [rules-users] NullPointerException with Wrapper objects
>> > To: rules-users at lists.jboss.org
>> >
>> >
>> > Well, like Wolfgang said, good luck with that. :) The only rules engine
>> I know that does this is Tibco BusinessEvents, and it's accomplished by
>> making a copy of your objects before inserting them into working memory.
>> >
>> > >From this forum post I'm guessing JRules doesn't do it:
>> http://forums.ilog.com/brms/index.php?topic=1439.0
>> >
>> > And probably Blaze Advisor doesn't do it either:
>> >
>> http://discuss.fico.com/blaze/board/message?board.id=Blaze_Advisor_Users_Forum&message.id=591
>> >
>> > So, I'm thinking you're stuck with having to do null checks.
>> >
>>
>>
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