[rules-users] Calling a method in when part

[Wolfgang Laun]

On 10 August 2011 17:14, Sumeet Karawal <sumeet.karawal at tcs.com> wrote:

>
>
> package rules.person
>
> import com.person.Age
> Import com.person.Classification
>
> rule "Check_person.option1"
>
> when
>
> $age : com.person.Age()
> $classification : com.person.Classification()
>

If you import, you can use just "Age" and "Classification".


>
> eval ($age.getClassification("16"))
>

This is not correct since the return value of Age.getClassification is not a
boolean.

As you present this code, it doesn't make any sense. The condition is a join
of an Age object and a Classification object and the argument of
getClassification("16") is a literal.

Providing an object to collect results is one reasonable way of doing it.

-W



>
> then
>
> modify ($classification) {$classification.setResult('"Teenager"; }
>
> end
>
> rule "Check_person.option2"
>
> when
>
> $age : com.person.Age()
> $classification : com.person.Classification()
>
> eval ($age.getClassification("40"))
>
> then
>
> modify ($classification) {$classification.setResult('"Adult"; }
>
> end
>
>
> Application Class :
>
> public class Age
> {
>        public string getClassification(String name) {
>                <Logic of the application>
>                return str;
>        }
> }
>
> public class Classification
> {
>        public void setResult(String name) {
>                <Logic of the application>
>
>        }
> }
>
>
>
> Queries :
>
>   Please let me know if I am using the 'when' part correctly.
>   And please check for the use of the object 'classification' in my
>   application (as return value to the application)
>
>
>
>
> Thanks & Regards,
> Sumeet Karawal
> Mailto: sumeet.karawal at tcs.com
>
>
>
>   From:       Wolfgang Laun <wolfgang.laun at gmail.com>
>
>  To:         Rules Users List <rules-users at lists.jboss.org>
>
>  Date:       08/10/2011 03:03 PM
>
>  Subject:    Re: [rules-users] Calling a method in when part
>
>  Sent by:    rules-users-bounces at lists.jboss.org
>
>
>
>
>
>
> If you don't show your code we can't tell you what is wrong with it. So I
> think what you may have to do is
>
> when
>    $someObj: SomeClass()  # matches each WME of SomeClass
>    eval( $someObj.getValueBoolean("abc"))
> then
>
> There is not much to be gained by using a DRL function; it would have to be
> called like
>    eval( someFunction( $someObj, "abc" ) )
>
> -W
>
>
> On 10 August 2011 11:05, Sumeet Karawal <sumeet.karawal at tcs.com> wrote:
>
>  Hi,
>
>  I have a requirement where there is a customized Java class having a
>  method
>  that returns some value.
>  like:
>
>  getValueBoolean("Some String")
>
>  { //some calculation
>    // returns a boolean value
>  }
>
>  The default getters and setters are not being used in the Application.
>  The
>  value that is being returned by the method needs to be checked in
>  the .drl
>  file.
>  There are different Java classes with these kind of methods. Where the
>  string and integer value is also returned. I have gone through the
>  documentation for Drools-Expert but have only found the implementation
>  for
>  the method in the consequence part, i.e., the then part.
>
>  This is how I tried:
>
>  importing the class
>
>  in when
>  binding the a variable to the Class name suppose $c
>  eval ($c.getValueBoolean("abc"))
>  then
>  System.out.println("the value is true")
>
>
>  It didn't work this way.
>  I tried by another way like :
>
>  creating a function in the .drl itself that calls the method of that
>  class
>  and returns a value
>  then calling this drl function in the when part and carrying on.
>
>  It would be very helpful if some body could let me know how to do this in
>  the .drl.
>
>
>  Thanks & Regards,
>  Sumeet Karawal
>  Mailto: sumeet.karawal at tcs.com
>
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