12:14 a.m.
I am facing problems which many have encountered in the past. I searched
forums but could not get precise answer. The problem is with null values in
Wrapper objects. See the following code:
rule "Null Check " salience 100
when
Salary ( ld : loanDeduction==null || < 0f ) // loanDeduction
is java.lang.Float
then
log("Load return is null"); //Global function
ld = 0f;
end
rule "Nett Salary" salience 70
when
Salary ( nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
You may have idea what I am trying to do. But I get NullPointerException in
“Nett Salary” rule when I fire the rules having fact with null in the
loanDeduction attribute. I believe my “Null Check” exception should execute
first and it does when I put negative value in loadDeduction. What is
solution in such a case?
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1:15 a.m.
All conditions of all applicable rules are evaluated when you insert an object into
working memory. This decides which rule actions can go on the agenda. Only when a rule
action is on the agenda is the salience used to determine the order of action firing. So
doing the null check in the way you're doing it will not work.
You must put the null check in the same rule, before the potentially null property is
used.
rule "Nett Salary" salience 70
when
Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
--- On Wed, 5/13/09, dhai <sdhari(a)hotmail.com> wrote:
From: dhai <sdhari(a)hotmail.com>
Subject: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
Date: Wednesday, May 13, 2009, 12:14 AM
I am facing problems which many have encountered in the
past. I searched
forums but could not get precise answer. The problem is
with null values in
Wrapper objects. See the following code:
rule "Null Check " salience 100
when
Salary ( ld : loanDeduction==null || <
0f ) // loanDeduction
is java.lang.Float
then
log("Load return is null");
//Global function
ld = 0f;
end
rule "Nett Salary" salience 70
when
Salary ( nett != ( gross – loanDeduction
– pf) )
then
log("Invalid nett salary
amount");
end
You may have idea what I am trying to do. But I get
NullPointerException in
“Nett Salary” rule when I fire the rules having fact
with null in the
loanDeduction attribute. I believe my “Null Check”
exception should execute
first and it does when I put negative value in
loadDeduction. What is
solution in such a case?
--
View this message in context:
http://www.nabble.com/NullPointerException-with-Wrapper-objects-tp2351550...
Sent from the drools - user mailing list archive at
Nabble.com.
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
1:26 a.m.
I know this
work around. But I have more than 50 rules using that attribute and it looks
very ugly to put null on every rule and its not single attribute. There are
more than 30 attributes in the bean and using them in LHS. Any other sophisticated
way?
Date: Tue, 12 May 2009 23:15:54 -0700
From: greg_barton(a)yahoo.com
Subject: Re: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
All conditions of all applicable rules are evaluated when you insert an object into
working memory. This decides which rule actions can go on the agenda. Only when a rule
action is on the agenda is the salience used to determine the order of action firing. So
doing the null check in the way you're doing it will not work.
You must put the null check in the same rule, before the potentially null property is
used.
rule "Nett Salary" salience 70
when
Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
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2:01 a.m.
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that
attribute and it looks very ugly to put null on every rule and its not
single attribute. There are more than 30 attributes in the bean and using
them in LHS. Any other sophisticated way?
> Date: Tue, 12 May 2009 23:15:54 -0700
> From: greg_barton(a)yahoo.com
> Subject: Re: [rules-users] NullPointerException with Wrapper objects
> To: rules-users(a)lists.jboss.org
>
>
> All conditions of all applicable rules are evaluated when you insert an
object into working memory. This decides which rule actions can go on the
agenda. Only when a rule action is on the agenda is the salience used to
determine the order of action firing. So doing the null check in the way
you're doing it will not work.
>
> You must put the null check in the same rule, before the potentially null
property is used.
>
> rule "Nett Salary" salience 70
> when
> Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
> then
> log("Invalid nett salary amount");
> end
>
------------------------------
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3:12 a.m.
I can not initialize property as need to log the message. The bean comes from outside our
application scope. We do not have control to make them menodatory. And we need to log the
message. You mean there is no solution of this problem? And remember my second rule does
not compare propery but it performs some calculations.
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that attribute and it looks
very ugly to put null on every rule and its not single attribute. There are more than 30
attributes in the bean and using them in LHS. Any other sophisticated way?
Date: Tue, 12 May 2009 23:15:54 -0700
From: greg_barton(a)yahoo.com
Subject: Re: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
All conditions of all applicable rules are evaluated when you insert
an object into working memory. This decides which rule actions can go on the agenda. Only
when a rule action is on the agenda is the salience used to determine the order of action
firing. So doing the null check in the way you're doing it will not work.
You must put the null check in the same rule, before the potentially null property is
used.
rule "Nett Salary" salience 70
when
Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
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3:36 a.m.
But you do control the insertion of your facts. Rather than cluttering rules
with conditions dealing with irregular values, preprocess the object. And
you should be able to log from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message. The bean
comes
from outside our application scope. We do not have control to make them
menodatory. And we need to log the message. You mean there is no solution of
this problem? And remember my second rule does not compare propery but
it performs some calculations.
------------------------------
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that
attribute and it looks very ugly to put null on every rule and its not
single attribute. There are more than 30 attributes in the bean and using
them in LHS. Any other sophisticated way?
> Date: Tue, 12 May 2009 23:15:54 -0700
> From: greg_barton(a)yahoo.com
> Subject: Re: [rules-users] NullPointerException with Wrapper objects
> To: rules-users(a)lists.jboss.org
>
>
> All conditions of all applicable rules are evaluated when you insert an
object into working memory. This decides which rule actions can go on the
agenda. Only when a rule action is on the agenda is the salience used to
determine the order of action firing. So doing the null check in the way
you're doing it will not work.
>
> You must put the null check in the same rule, before the potentially null
property is used.
>
> rule "Nett Salary" salience 70
> when
> Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
> then
> log("Invalid nett salary amount");
> end
>
------------------------------
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3:44 a.m.
Well I cant explain you all the issues and requirements here. Simply we dont have
provision to do so. We have to check the null in the rules and log the message plus other
evaluation and arithmetic.
Date: Wed, 13 May 2009 10:36:59 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
But you do control the insertion of your facts. Rather than cluttering rules with
conditions dealing with irregular values, preprocess the object. And you should be able to
log from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message. The bean comes from outside our
application scope. We do not have control to make them menodatory. And we need to log the
message. You mean there is no solution of this problem? And remember my second rule does
not compare propery but it performs some calculations.
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that attribute and it looks
very ugly to put null on every rule and its not single attribute. There are more than 30
attributes in the bean and using them in LHS. Any other sophisticated way?
Date: Tue, 12 May 2009 23:15:54 -0700
From: greg_barton(a)yahoo.com
Subject: Re: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
All conditions of all applicable rules are evaluated when you insert
an object into working memory. This decides which rule actions can go on the agenda. Only
when a rule action is on the agenda is the salience used to determine the order of action
firing. So doing the null check in the way you're doing it will not work.
You must put the null check in the same rule, before the potentially null property is
used.
rule "Nett Salary" salience 70
when
Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
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5:19 a.m.
Well, I hope you get paid for all the extra work ;-)
Define, in your .drl file,
function float safe( Float v ){
return v == null ? 0 : v;
}
and wrap all references to the "dangerous" field(s) in your LHS pattern
expressions with this call, except, of course, in the rule where you fix and
log the field.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
Well I cant explain you all the issues and requirements here. Simply
we
dont have provision to do so. We have to check the null in the rules and log
the message plus other evaluation and arithmetic.
------------------------------
Date: Wed, 13 May 2009 10:36:59 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
But you do control the insertion of your facts. Rather than cluttering
rules with conditions dealing with irregular values, preprocess the object.
And you should be able to log from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message. The bean comes
from outside our application scope. We do not have control to make them
menodatory. And we need to log the message. You mean there is no solution of
this problem? And remember my second rule does not compare propery but
it performs some calculations.
------------------------------
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that attribute
and it looks very ugly to put null on every rule and its not single
attribute. There are more than 30 attributes in the bean and using them in
LHS. Any other sophisticated way?
> Date: Tue, 12 May 2009 23:15:54 -0700
> From: greg_barton(a)yahoo.com
> Subject: Re: [rules-users] NullPointerException with Wrapper objects
> To: rules-users(a)lists.jboss.org
>
>
> All conditions of all applicable rules are evaluated when you insert an
object into working memory. This decides which rule actions can go on the
agenda. Only when a rule action is on the agenda is the salience used to
determine the order of action firing. So doing the null check in the way
you're doing it will not work.
>
> You must put the null check in the same rule, before the potentially null
property is used.
>
> rule "Nett Salary" salience 70
> when
> Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
> then
> log("Invalid nett salary amount");
> end
>
------------------------------
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5:44 a.m.
Thanks for all you efforts :) but what is the difference between calling function from
every rule or putting null check. I give up. I am looking for other rule engines.
Date: Wed, 13 May 2009 12:19:08 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
Well, I hope you get paid for all the extra work ;-)
Define, in your .drl file,
function float safe( Float v ){
return v == null ? 0 : v;
}
and wrap all references to the "dangerous" field(s) in your LHS pattern
expressions with this call, except, of course, in the rule where you fix and log the
field.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
Well I cant explain you all the issues and requirements here. Simply we dont have
provision to do so. We have to check the null in the rules and log the message plus other
evaluation and arithmetic.
Date: Wed, 13 May 2009 10:36:59 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
But you do control the insertion of your facts. Rather than cluttering rules with
conditions dealing with irregular values, preprocess the object. And you should be able to
log from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message. The bean comes from outside our
application scope. We do not have control to make them menodatory. And we need to log the
message. You mean there is no solution of this problem? And remember my second rule does
not compare propery but it performs some calculations.
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that attribute and it looks
very ugly to put null on every rule and its not single attribute. There are more than 30
attributes in the bean and using them in LHS. Any other sophisticated way?
Date: Tue, 12 May 2009 23:15:54 -0700
From: greg_barton(a)yahoo.com
Subject: Re: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
All conditions of all applicable rules are evaluated when you insert
an object into working memory. This decides which rule actions can go on the agenda. Only
when a rule action is on the agenda is the salience used to determine the order of action
firing. So doing the null check in the way you're doing it will not work.
You must put the null check in the same rule, before the potentially null property is
used.
rule "Nett Salary" salience 70
when
Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
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7 a.m.
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
Thanks for all you efforts :) but what is the difference between
calling
function from every rule or putting null check.
It's much easier to add.
I give up. I am looking for other rule engines.
As they must apparently (due to JavaBeans) be Java-based, I'd be very much
surprised if you'll find what you are looking for.
-W
------------------------------
Date: Wed, 13 May 2009 12:19:08 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
Well, I hope you get paid for all the extra work ;-)
Define, in your .drl file,
function float safe( Float v ){
return v == null ? 0 : v;
}
and wrap all references to the "dangerous" field(s) in your LHS pattern
expressions with this call, except, of course, in the rule where you fix and
log the field.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
Well I cant explain you all the issues and requirements here. Simply we
dont have provision to do so. We have to check the null in the rules and log
the message plus other evaluation and arithmetic.
------------------------------
Date: Wed, 13 May 2009 10:36:59 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
But you do control the insertion of your facts. Rather than cluttering
rules with conditions dealing with irregular values, preprocess the object.
And you should be able to log from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message. The bean comes
from outside our application scope. We do not have control to make them
menodatory. And we need to log the message. You mean there is no solution of
this problem? And remember my second rule does not compare propery but
it performs some calculations.
------------------------------
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules using that attribute
and it looks very ugly to put null on every rule and its not single
attribute. There are more than 30 attributes in the bean and using them in
LHS. Any other sophisticated way?
> Date: Tue, 12 May 2009 23:15:54 -0700
> From: greg_barton(a)yahoo.com
> Subject: Re: [rules-users] NullPointerException with Wrapper objects
> To: rules-users(a)lists.jboss.org
>
>
> All conditions of all applicable rules are evaluated when you insert an
object into working memory. This decides which rule actions can go on the
agenda. Only when a rule action is on the agenda is the salience used to
determine the order of action firing. So doing the null check in the way
you're doing it will not work.
>
> You must put the null check in the same rule, before the potentially null
property is used.
>
> rule "Nett Salary" salience 70
> when
> Salary ( loanDeduction != null, nett != ( gross – loanDeduction – pf) )
> then
> log("Invalid nett salary amount");
> end
>
------------------------------
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10:28 a.m.
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_...
So, I'm thinking you're stuck with having to do null checks.
--- On Wed, 5/13/09, Shabbir Dhari <sdhari(a)hotmail.com> wrote:
From: Shabbir Dhari <sdhari(a)hotmail.com>
Subject: RE: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)lists.jboss.org
Date: Wednesday, May 13, 2009, 5:44 AM
Thanks for all you efforts :) but what is the difference
between calling function from every rule or putting null
check. I give up. I am looking for other rule engines.
Date: Wed, 13 May 2009 12:19:08 +0200
Subject: Re: [rules-users] NullPointerException with
Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
Well, I hope you get paid for all the extra work ;-)
Define, in your .drl file,
function float safe( Float v ){
return v == null ? 0 : v;
}
and wrap all references to the "dangerous"
field(s) in your LHS pattern expressions with this call,
except, of course, in the rule where you fix and log the
field.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
Well I cant explain you all the issues and requirements
here. Simply we dont have provision to do so. We have to
check the null in the rules and log the message plus other
evaluation and arithmetic.
Date: Wed, 13 May 2009 10:36:59 +0200
Subject: Re: [rules-users] NullPointerException with
Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
But you do control the insertion of your facts. Rather than
cluttering rules with conditions dealing with irregular
values, preprocess the object. And you should be able to log
from there, just as well.
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I can not initialize property as need to log the message.
The bean comes from outside our application scope. We do not
have control to make them menodatory. And we need to log the
message. You mean there is no solution of this problem? And
remember my second rule does not compare propery but it
performs some calculations.
Date: Wed, 13 May 2009 09:01:05 +0200
Subject: Re: [rules-users] NullPointerException with
Wrapper objects
From: wolfgang.laun(a)gmail.com
To: rules-users(a)lists.jboss.org
What about setting the field to 0 in the constructor of
Salary?
Or using float (not java.lang.Float)?
-W
2009/5/13 Shabbir Dhari <sdhari(a)hotmail.com>
I know this work around. But I have more than 50 rules
using that attribute and it looks very ugly to put null on
every rule and its not single attribute. There are more than
30 attributes in the bean and using them in LHS. Any other
sophisticated way?
> Date: Tue, 12 May 2009 23:15:54 -0700
> From: greg_barton(a)yahoo.com
> Subject: Re: [rules-users] NullPointerException with
Wrapper objects
> To: rules-users(a)lists.jboss.org
>
>
> All conditions of all applicable rules are evaluated
when you insert an object into working memory. This decides
which rule actions can go on the agenda. Only when a rule
action is on the agenda is the salience used to determine
the order of action firing. So doing the null check in the
way you're doing it will not work.
>
> You must put the null check in the same rule, before
the potentially null property is used.
>
> rule "Nett Salary" salience 70
> when
> Salary ( loanDeduction != null, nett != ( gross –
loanDeduction – pf) )
> then
> log("Invalid nett salary amount");
> end
>
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5:27 p.m.
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(a)yahoo.com
Subject: RE: [rules-users] NullPointerException with Wrapper objects
To: rules-users(a)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_...
So, I'm thinking you're stuck with having to do null checks.
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1:02 a.m.
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(a)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(a)yahoo.com
> Subject: RE: [rules-users] NullPointerException with Wrapper objects
> To: rules-users(a)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_...
>
> So, I'm thinking you're stuck with having to do null checks.
>
------------------------------
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7:59 a.m.
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(a)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(a)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(a)yahoo.com
> > Subject: RE: [rules-users] NullPointerException with Wrapper objects
> > To: rules-users(a)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_...
> >
> > So, I'm thinking you're stuck with having to do null checks.
> >
>
>
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8:05 a.m.
I am no expert on drools; however, you might want to retract loanDeduction
from the Working Memory if it is null. Your first rule determines that it
is null and then you set the value (ld = 0f); however, you should be using
an insert to put this into working memory. The other alternative is to
retract the loan Deduction from working memory and add a logic check in the
Nett Salary rule to see if loan Dedcution is null.
I am working on some Drools stuff today if you need some more help on this.
Shannon
On Wed, May 13, 2009 at 1:14 AM, dhai <sdhari(a)hotmail.com> wrote:
I am facing problems which many have encountered in the past. I searched
forums but could not get precise answer. The problem is with null values in
Wrapper objects. See the following code:
rule "Null Check " salience 100
when
Salary ( ld : loanDeduction==null || < 0f ) // loanDeduction
is java.lang.Float
then
log("Load return is null"); //Global function
ld = 0f;
end
rule "Nett Salary" salience 70
when
Salary ( nett != ( gross – loanDeduction – pf) )
then
log("Invalid nett salary amount");
end
You may have idea what I am trying to do. But I get NullPointerException in
“Nett Salary” rule when I fire the rules having fact with null in the
loanDeduction attribute. I believe my “Null Check” exception should execute
first and it does when I put negative value in loadDeduction. What is
solution in such a case?
--
View this message in context:
http://www.nabble.com/NullPointerException-with-Wrapper-objects-tp2351550...
Sent from the drools - user mailing list archive at Nabble.com.
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14 comments
5 participants
participants (5)
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dhai -
Greg Barton -
Shabbir Dhari
-
Shannon Lal -
Wolfgang Laun