I had same problem with 4M2 release. Please upgrade it to either 4.0.0 GA or
4M3 release.
You can also find a sample example ShoppingExample.java and Shopping.drl,
which is self-explanatory.
However, I was not able to test few MVEL features like projections, which i
think if added would make drools even more dynamic.

Thanks,
manjax23


Richard Hoberman wrote:
  

1. I can't find any mention of dialects anywhere in the Drools 4
manual.  Am I missing something?

2. I've tried the following after finding a snippet in the archives for
this list:

    package mvanamibia.claim;

    import java.lang.Object;
    import java.lang.String;
    import java.lang.Double;
    import java.util.Date;
    import java.util.List;
    import java.util.ArrayList;
    import com.sadalbari.mvanamibia.beans.Claim;
    import com.sadalbari.mvanamibia.beans.Mandate;
    import com.sadalbari.mvanamibia.beans.SubmissionInfo;
    import com.sadalbari.mvanamibia.inspector.ClaimEvaluation;

    global ClaimEvaluation evaluation;

    rule "hasDateReceived"
        dialect "mvel"
        when
            Claim( submissionInfo == null )
        then
            evaluation.getViolations().add("missing: date received");
    end


but it gives the following exception:

    java.lang.NullPointerException
        at
   
org.drools.rule.builder.RuleBuildContext.<init>(RuleBuildContext.java:115)
        at
    org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:350)
        at
    org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:233)
        at
   
org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:157)
        at
   
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.setupWorkingMemory(UnregisteredClaimValidationTest.java:29)
        at
   
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.testEmptyClaim(UnregisteredClaimValidationTest.java:42)
    ... Removed 22 stack frames


Thanks

Richard


Mark Proctor wrote:
    

in theory for nested accessors it should switch to the MVEL dialect
automatically. You only need to specify the MVEL dialect explicitely
for eval, return value and consequences.

Mark
Manjax23 wrote:
      

I think you should use dialect "mvel" when accessing the nested
accessors.
and I had some trouble with "mvel" dialect in 4M2 release.

Please let me know if it works for you..

Thanks,
Manjax23


Richard Hoberman wrote:
  
        

I'm using Drools 4 (M2), which is supposed to support nested accessors*

This works: when Claim( submissionInfo == null), but not this: when
Claim( submissionInfo.date == null)

Rule file, SubmissionInfo.java and exception are below.

What am I missing?

Richard




* See
http://article.gmane.org/gmane.comp.java.drools.user/8079/match=nested+properties,
which states "Support to nested accessors, property navigation and
simplified collection, arrays and maps syntax"

Rule File

---------------------------------------------------------------------------------------
package mvanamibia.claim;

import java.lang.Object;
import java.lang.String;
import java.lang.Double;
import java.util.Date;
import java.util.List;
import java.util.ArrayList;
import com.sadalbari.mvanamibia.beans.Claim;
import com.sadalbari.mvanamibia.beans.Mandate;
import com.sadalbari.mvanamibia.beans.SubmissionInfo;
import com.sadalbari.mvanamibia.inspector.ClaimEvaluation;

global ClaimEvaluation evaluation;

rule "hasDateReceived"

    when
        Claim( submissionInfo.date == null )
    then
        evaluation.getFailures().add("missing: date received");
end

-----------------------------------------------------------------------------------

Exception
-----------------------------------------------------------------------------------
org.drools.rule.InvalidRulePackage: [19,23]: unknown:19:23 mismatched
token: [@137,471:471='.',<69>,19:23]; expecting type RIGHT_PAREN
    at org.drools.rule.Package.checkValidity(Package.java:368)
    at
org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:250)
    at
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.setupWorkingMemory(UnregisteredClaimValidationTest.java:33)
    at
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.testMandateClaim(UnregisteredClaimValidationTest.java:56)
... Removed 22 stack frames
FAILED: testEmptyClaim
org.drools.rule.InvalidRulePackage: [19,23]: unknown:19:23 mismatched
token: [@137,471:471='.',<69>,19:23]; expecting type RIGHT_PAREN
    at org.drools.rule.Package.checkValidity(Package.java:368)
    at
org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:250)
    at
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.setupWorkingMemory(UnregisteredClaimValidationTest.java:33)
    at
com.sadalbari.mvanamibia.model.UnregisteredClaimValidationTest.testEmptyClaim(UnregisteredClaimValidationTest.java:42)
... Removed 22 stack frames


------------------------------------------------------
SubmissionInfo (relevant bits)

public class SubmissionInfo implements Serializable {

    private Date date;

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }


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