use of enum with "in" on LHS

[dsykes]

Hi there,

I have a rule where I would like human-readable rule to have a comma separated list of enum constants in it, however I can't find a way to get this working.

DSLR file:

import com.test.Report;
import com.test.RulesResult;
import com.test.State;

rule "Test rule"
    when
        the received object
        - state is NEW, MODIFY
    then
        #unimportant
end

DSL file:

[*][when]the received object=result : RulesResult();$stm : Report()
[*][when]- state is {stateList}=state in (State.{stateList})

Class Report has a property called state which is an enum of type State which has a number of constants including NEW and MODIFY.

When I run this I get:

org.drools.RuntimeDroolsException: Exception executing predicate ( state == State.NEW || state == MODIFY)

As you can see only the first constant is being qualified with the enum class.  Can anyone help me with how to do this properly?

Thanks,
Derek

[FrankVhh]

Hi,

Unless there is another workaround, I think you would have to do it something like this:

[*][when]the received object=result : RulesResult();$stm : Report()
[*][keyword]NEW=State.NEW
[*][keyword]OLD=State.OLD
[*][when]- state is {stateList}=state in ({stateList})

Regards,
Frank

[laune]

Regrettably, this is just a string substitution, not caring what it
is, or what comes before or after.
-W

On 16/05/2012, dsykes <[hidden email]> wrote:

> Hi there,
>
> I have a rule where I would like human-readable rule to have a comma
> separated list of enum constants in it, however I can't find a way to get
> this working.
>
> DSLR file:
>
> import com.test.Report;
> import com.test.RulesResult;
> import com.test.State;
>
> rule "Test rule"
>     when
>         the received object
>         - state is NEW, MODIFY
>     then
>         #unimportant
> end
>
> DSL file:
>
> [*][when]the received object=result : RulesResult();$stm : Report()
> [*][when]- state is {stateList}=state in (State.{stateList})
>
> Class Report has a property called state which is an enum of type State
> which has a number of constants including NEW and MODIFY.
>
> When I run this I get:
>
> org.drools.RuntimeDroolsException: Exception executing predicate ( state ==
> State.NEW || state == MODIFY)
>
> As you can see only the first constant is being qualified with the enum
> class.  Can anyone help me with how to do this properly?
>
> Thanks,
> Derek
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/use-of-enum-with-in-on-LHS-tp3997081.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> [hidden email]
> https://lists.jboss.org/mailman/listinfo/rules-users
>

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[laune]

But take care, this replaces *all* occurrences of the words NEW and OLD.
-W

On 16/05/2012, FrankVhh <[hidden email]> wrote:

> Hi,
>
> Unless there is another workaround, I think you would have to do it
> something like this:
>
> [*][when]the received object=result : RulesResult();$stm : Report()
> [*][keyword]NEW=State.NEW
> [*][keyword]OLD=State.OLD
> [*][when]- state is {stateList}=state in ({stateList})
>
> Regards,
> Frank
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/use-of-enum-with-in-on-LHS-tp3997081p3997136.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> [hidden email]
> https://lists.jboss.org/mailman/listinfo/rules-users
>

_______________________________________________
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[hidden email]
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[dsykes]

Hey Frank,

It's not perfect but it should serve the purpose and is far preferable to the alternatives I was considering.  Thanks very much!

Cheers,
Derek

[Vincent Legendre]

Another potentiel trick :

In State enum, add a method to build a State list from a list of string
enum State {
    ...
    static List<State> buildList(String listAsStr) {
        // well, don't need to detail that ...
        // ... but think to keep a cache somewhere to avoid unecessary iterations at each rule's evaluation ...
    }
}

and in your DSL :
[*][when]- state is {stateList}=state in (State.buildList({stateList}))


Don't know if it really works, just an idea that could be better than replacing all NEW/OLD strings ...
If ot works, it can even be better to handle weird items list in a big string ...
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