If you can add the CatalogObject element data to working memory and if you can add a connective property ("parent" in the rule below) you can eliminate the use of "eval" (which does not allow the benefits of a RETE network to be fully realised) I think a rule like the below using 3.1-M1 would provide the same function as that shown by Michael Neale. Lots of assumptions but performance would be better.

rule "UCCnet_DVE_Depth_All"

when

catalogObject : CatalogObject( )

elementValue( name = "depth", value == null | == "", parent == catalogObject )

then

logWriter.logDebug( "Package Depth is Blank");

System.out.println( "Package Depth is Blank" );

end

With kind regards,

Mike

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Michael Neale
Sent: 04 April 2007 05:18
To: Rules Users List
Subject: Re: [rules-users] Need DRL authoring Help

you are close ;)

Yes, it is a challenge, thats what the examples are for etc.

but try this (FYI I think you mean "or"):

rule "UCCnet_DVE_Depth_All"

      when

            catalogObject : CatalogObject( )

         eval( catalogObject.getElementValue( "depth") == null || catalogObject.getElementValue( "depth") == "" )

#           String depth = CatalogObject.getElementValue("depth")

#           depth == null

#           depth == ""

#           catalogObject : CatalogObject( depth == null)

#           catalogObject : CatalogObject( depth == "")

      then

   # DON'T do this            logWriter : LogWriter();

        # BUT you can pass in a logWriter global variable

            logWriter.logDebug( "Package Depth is Blank");

            System.out.println( "Package Depth is Blank" );
end

Hope that helps.
In the up coming BRMS, there will be a GUI which also has a secret purpose of "coaching" what DRL looks like, for those who need to know.

On 4/4/07, John.Tal@gxs.com <John.Tal@gxs.com> wrote:

Writing DRL is not easy for people new to drools.   Can someone please help me understand how to write this simple rule? You can see the approaches I have taken.

In this case I do not have getters and setters for the attributes I am checking. I need to pass parameters to the object for it to get the data.

I can't get any of the code in the when block to be syntax proper. Existing DRL doc is lacking in this area.

Thanks John

rule "UCCnet_DVE_Depth_All"

      when

            catalogObject : CatalogObject( getElementValue( "depth") == null, getElementValue( "depth") == "")

#           String depth = CatalogObject.getElementValue("depth")

#           depth == null

#           depth == ""

#           catalogObject : CatalogObject( depth == null)

#           catalogObject : CatalogObject( depth == "")

      then

            logWriter : LogWriter();

            logWriter.logDebug( "Package Depth is Blank");

            System.out.println( "Package Depth is Blank" );

end

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