2011/8/5 Gaurav Silakari <gaurav.silakari@tcs.com>

Below is my drl and the Pojo that I am using, please guide me on this :

#created on: Aug 5, 2011
package com.sample
import com.sample.Customer

rule "Below 100"

when
$c:Customer()
$c.getSi() < 100

$c: Customer( si < 100 )
This is the proper way of making a constraint on a fact attribute. "getSi" and "si" relate according to JavaBeans.

then
$c.setVal("<100");

end

rule "Below 200"

when
$c:Customer()
$c.getSi() < 200

# Same as above.
You realize that <100 also means <200; if so, both rules will fire and "val" could be set either way.

then
$c.setVal("<200");

end

rule "Below 300"

when
$c:Customer()
$c.getSi() < 300

# see comment on rule "Below 200"

-W

then
$c.setVal("<300");

end

Pojo :

package com.sample;

public class Customer {

private double si;
private String val;

public double getSi() {
return si;
}
public double setSi(double p,double r, double t) {
si = (p*r*t)/100;
return si;
}
public String getVal() {
return val;
}
public void setVal(String val) {
this.val = val;
}

}

The error that I get while executing is :

[9,13]: unknown:9:13 mismatched token: [@33,126:126='<',<79>,9:13]; expecting type THEN[20,13]: unknown:20:13 mismatched token: [@67,224:224='<',<79>,20:13]; expecting type THEN[32,13]: unknown:32:13 mismatched token: [@101,323:323='<',<79>,32:13]; expecting type THEN
java.lang.RuntimeException: Unable to compile "methodCall.drl".
at com.sample.Calling.createRuleBase(Calling.java:48)
at com.sample.Calling.main(Calling.java:24)

and my calling class is :

package com.sample;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;

import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.StatefulSession;
import org.drools.compiler.PackageBuilder;
import org.drools.rule.Package;

public class Calling {

public static void main(String[] args)throws IOException {

Customer c1 = new Customer();
c1.setSi(1000, 5, 2);

try {

RuleBase ruleBase = createRuleBase();
StatefulSession session = ruleBase.newStatefulSession ();

session.insert(c1);
session.fireAllRules();
session.dispose();

System.out.println("Interest is : "+c1.getVal());

}
catch (Throwable t) {
t.printStackTrace();
}
}

private static RuleBase createRuleBase() throws Exception
{
Reader source = new InputStreamReader(Calling.class.getResourceAsStream( "methodCall.drl" ) );

PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl( source );

if ( builder.hasErrors() ) {
System.out.println( builder.getErrors().toString() );
throw new RuntimeException( "Unable to compile \"methodCall.drl\".");
}

Package pkg = builder.getPackage();
RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage( pkg );

return ruleBase;

}

}