[rules-users] Java Enums in Guvnor

[Ansgar Konermann]

Hi Ian,

I tried using Enums with Guvnor twice: once back in the 4.0 times of 
Drools, once again when we got the 5.0 update.

My experience: Java enums and Guvnor simply don't work together. Stick 
with writing DRL rule files in a text editor, or even better, using the 
Eclipse plugin. This way, enums work somehow (still no code completion 
for enum values, even when using the Eclipse plugin). If for some reason 
you must use guvnor, you'll probably need to convert your beans 
properties now holding Java enums into properties of type String and use 
string constants to define the allowed value range.

Guvnor experts: I'd be very happy to be proven wrong by someone of you. 
Some kind of "HOWTO use Java Enums in Guvnor correctly" blog post etc. 
very much appreciated ;-)

Best regards

Ansgar


On 19.05.2010 18:36, Ian-D.Jones at ubs.com wrote:

> Hi All,
> I've recently started using Drools and Guvnor, and so far really like it!
> I have one problem however, to do with Java enums in Guvnor.
> I have a simple enum as follows:
> **
>
> *public* *enum* STPRuleAction
> {
> / UNKNOWN/, /ACCEPT/, /REJECT//
> /}
>
> I can hand write a rule that works fine with this enum as follows:
> **
>
> *rule* "Retract rejected"
> * dialect* "mvel"
> * when
> * o : CtasOrder( stpRuleAction == STPRuleAction.REJECT )
> * then
> * o.setStatus( 1 );
> * retract*( o );
> *end*
>
> However, if I create a rule with Guvnor, it always puts quotes around 
> the condition, so seems to treat it as a string and it is never 
> triggered. I have created a Guvnor enumeration as follows:
> 'CtasOrder.stpRuleAction' : ['STPRuleAction.UNKNOWN=UNKNOWN', 
> 'STPRuleAction.ACCEPT=ACCEPT', 'STPRuleAction.REJECT=REJECT']
> Which gives me the correct drop down values in the Business Rule 
> editor, but the source of the rule looks like:
>
> *rule* "Retract rejected"
> * dialect* "mvel"
> * when
> * o : CtasOrder( stpRuleAction == *"STPRuleAction.REJECT"*)
> * then
> * o.setStatus( 1 );
> * retract*( o );
> *end*
>
> I've tried without the mapping in the enumeration (e.g ... : 
> ['STPRuleAction.UNKNOWN', ...) and even removing the enumeration and 
> adding the text manually as a literal value. I can't see any way to 
> specfy a enum/qualifiedIdentifier as a condition in Guvnor. It works 
> fine as a consequence and produces a rule without quotes around (e.g. 
> o.setStpRuleAction( STPRuleAction.REJECT )...)
> Many thanks for any assistance you can give.
> Regards,
> Ian
>
>
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>    

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