[rules-users] Accessing maps (hashmaps) keys and values in rules
Shaz Tumulak
shauii at yahoo.com
Thu Nov 1 03:35:52 EDT 2007
Hi,
I can't seem to make this syntax work in Drools 4.0.2. Pls. see my sample
code below.
________________________________________
class MyClass {
String id;
String name;
MyClass(String id, String name){
this.id = id;
this.name = name;
}
:
getter, setter methods
:
}
MyClass obj = new MyClass("1"", "name");
TreeMap<String, MyClass> mapOfObj = new TreeMap<String, MyClass>();
mapOfObj.put("keyOfObj", obj);
________________________________________
DRL file
-------
global java.util.TreeMap mapOfObj;
rule chkobj
when
obj : MyClass(mapOfObj["keyOfObj"].id == "1");
eval(obj.getName() == "name");
________________________________________
I'm getting this error: org.drools.RuntimeDroolsException:
java.lang.NullPointerException
at
org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:76)
Is my syntax correct and has someone used this in 4.0.2 or should I move on
to Drools 4.0.3? Thanks in advance.
Regards,
shaz
Edson Tirelli-3 wrote:
>
> Denis,
>
> If you are using latest build from trunk (I'm not sure it already works
> in MR3), you can use a simplified MVEL syntax:
>
> when
> Person( address["business"].phone == "99999999" )
> then
> ...
> end
>
> Although, the above will be converted into an inline-eval. Not as bad
> as
> a top level eval, but still more costly then using regular fields.
>
> []s
> Edson
>
> 2007/7/19, Ryan, Dennis (Dennis) <dennisryan at avaya.com>:
>>
>> We are using Maps (HashMaps) in our rules and the only way we have found
>> to access keys and values in the Map in the "when" clauses is thru use on
>> eval() which I know is a big no-no by rules purists. Is there a better
>> way,
>> maybe some shorthand I'm not familiar with to deal with Maps in the when
>> clause?
>>
>>
>>
>> Thanks,
>>
>> Dennis
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>
>
> --
> Edson Tirelli
> Software Engineer - JBoss Rules Core Developer
> Office: +55 11 3529-6000
> Mobile: +55 11 9287-5646
> JBoss, a division of Red Hat @ www.jboss.com
>
> _______________________________________________
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>
>
shauii at yahoo.com
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