11:20 a.m.
Hello,
I would like to use type-safe enums in my rules. At the moment I have
situation like this:
public class Country {
private String name;
// getter/setters
}
rule "Country"
when
Country ( name == "USA" )
then
DO SOMETHING
end
I would like to have something like this:
public enum Country {
USA ()
// list of all countries in the world
}
and in the rule I would like to do this:
rule "Country"
when
Country ( name == Country.USA )
then
DO SOMETHING
end
Is that possible?
Thanks in advance for your help.
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12:03 p.m.
That rule would work if you added a “name” property to Country.
As a general tip on working with countries, always work with their ISO codes, not their
names.
http://en.wikipedia.org/wiki/ISO_3166-1
… ideally the 2-char codes, which are much more commonly used than the 3-char codes.
Feel free to steal this:
https://github.com/gratiartis/sctrcd-payment-validation-web/blob/master/s...
… which sets up all countries with ISO codes and full-text names as enums. Or at least all
countries which were included in the ISO spec at the time of writing.
Grab it while you can - I’m in the middle of refactoring it into a JPA entity. :)
Steve
On 12 Nov 2013, at 10:20, droolster <quant.coder(a)gmail.com> wrote:
Hello,
I would like to use type-safe enums in my rules. At the moment I have
situation like this:
public class Country {
private String name;
// getter/setters
}
rule "Country"
when
Country ( name == "USA" )
then
DO SOMETHING
end
I would like to have something like this:
public enum Country {
USA ()
// list of all countries in the world
}
and in the rule I would like to do this:
rule "Country"
when
Country ( name == Country.USA )
then
DO SOMETHING
end
Is that possible?
Thanks in advance for your help.
--
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1:23 p.m.
Using the same name for a fact class Country and an enum Country
will most certainly not be possible unless you use full class names for
disambiguation.
And, of course, the name property of fact class Country would have to
have the enum type.
-W
On 12/11/2013, Stephen Masters <stephen.masters(a)me.com> wrote:
That rule would work if you added a “name” property to Country.
As a general tip on working with countries, always work with their ISO
codes, not their names.
http://en.wikipedia.org/wiki/ISO_3166-1
… ideally the 2-char codes, which are much more commonly used than the
3-char codes.
Feel free to steal this:
https://github.com/gratiartis/sctrcd-payment-validation-web/blob/master/s...
… which sets up all countries with ISO codes and full-text names as enums.
Or at least all countries which were included in the ISO spec at the time of
writing.
Grab it while you can - I’m in the middle of refactoring it into a JPA
entity. :)
Steve
On 12 Nov 2013, at 10:20, droolster <quant.coder(a)gmail.com> wrote:
> Hello,
>
> I would like to use type-safe enums in my rules. At the moment I have
> situation like this:
>
> public class Country {
> private String name;
>
> // getter/setters
> }
>
> rule "Country"
> when
> Country ( name == "USA" )
> then
> DO SOMETHING
> end
>
> I would like to have something like this:
>
> public enum Country {
> USA ()
> // list of all countries in the world
> }
>
> and in the rule I would like to do this:
>
> rule "Country"
> when
> Country ( name == Country.USA )
> then
> DO SOMETHING
> end
>
> Is that possible?
>
> Thanks in advance for your help.
>
>
>
>
>
>
> --
> View this message in context:
>
http://drools.46999.n3.nabble.com/How-to-use-type-safe-enums-in-rule-cond...
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
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2:20 p.m.
Thanks Steve for the advice and code! Awesome.
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12:59 a.m.
I use something like the following in rules to good effect:
Country( this == Country.USA )
-------------------------------------------------------------------
Steven Williams
On Wed, Nov 13, 2013 at 12:20 AM, droolster <quant.coder(a)gmail.com> wrote:
Thanks Steve for the advice and code! Awesome.
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2:40 p.m.
Just curiosity.
On 13/11/2013, Steven Williams <stevearoonie(a)gmail.com> wrote:
I use something like the following in rules to good effect:
Country( this == Country.USA )
Granted, you can add any number of attributes to an enum so that it's
just another way of writing a static set of bean objects. But is there
a "good effect" to be had from a pattern that merely ascertains the
presence of an enum instance
in the Working Memory?
Other than this, a pattern like
City( country == Country.USA )
doesn't require the insertion of the Country enums.
Cheers
Wolfgang
12:07 a.m.
We use drools for validation rules in our application. Some of these rules
are dependent on which CRUD operation is being performed at the time, so as
part of our validation aspect we insert a CrudMode enum with the current
action (by annotating the advised method). e.g.
@Validate(validators = BusinessRulesValidator.class, mode = CREATE)
public void create(@DTO SomeDTO incomingDto)
In our rules we can then go:
CrudMode(this == CrudMode.CREATE)
The second way we use it (and this one I don't like so much) is that our
validation aspect runs both before and after a method (PRE and POST). We
use an agenda-group to to indicate which phase a rule should be included
which works fine, however we were finding that some conditions were
relatively expensive which had performance implications. Our solution was
to also include a ValidationPhase enum as a fact and use that to
short-circuit the rules. I reckon there is probably a better way to achieve
this however we didn't spend a lot of time thinking about it.
cheers
Steve
-------------------------------------------------------------------
Steven Williams
On Thu, Nov 14, 2013 at 12:40 AM, Wolfgang Laun <wolfgang.laun(a)gmail.com>wrote:
Just curiosity.
On 13/11/2013, Steven Williams <stevearoonie(a)gmail.com> wrote:
> I use something like the following in rules to good effect:
>
> Country( this == Country.USA )
Granted, you can add any number of attributes to an enum so that it's
just another way of writing a static set of bean objects. But is there
a "good effect" to be had from a pattern that merely ascertains the
presence of an enum instance
in the Working Memory?
Other than this, a pattern like
City( country == Country.USA )
doesn't require the insertion of the Country enums.
Cheers
Wolfgang
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6 comments
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participants (4)
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droolster -
Stephen Masters -
Steven Williams -
Wolfgang Laun