[rules-users] Find out order of insert in RHS

[Wolfgang Laun]

If object creation is done in the same order as the insertion: surely
a simple static counter in the class would give you the required
monotonous value.

Otherwise, a listener could be set, which will "see" the actual order
of insertion, and it can set the order-of-insertion property.

-W


On 07/02/2013, Sandjaja, Dominik <dominik.sandjaja at it-motive.de> wrote:
> Hi everybody,
>
> short: is there a way to have an automatic counter for the RHS of a rule
> when inserting several objects in one rule?
>
> Long:
> I use drools with a DSL to insert items for a frontend dropdown box. The
> generated rule is e.g. like the following one:
>
>     rule "testRule_H"
>         dialect "mvel"
>             when
>                 SomePartOfMyModel( someField == "H" )
>                     then
>                         DropDownItem fact1 = new DropDownItem();
> fact1.setLabel( "My Label 1" ); fact1.setValue( "B" );
>
> insert (fact1);
>                         DropDownItem fact1 = new DropDownItem();
> fact1.setLabel( "My Label 2" ); fact1.setValue( "A" );
>
> insert (fact1);
>
> This works nicely and I get all the items. The problem I have is with the
> sorting. Users use Guvnor to edit the available items for the dropdown box,
> so they add and remove items from the RHS. Since I retrieve those objects
> from the knowledge base in my java code like this:
>
> Collection<FactHandle> handles = statefulKnowledgeSession.getFactHandles(new
> ClassObjectFilter(DropDownItem.class));
>         for (FactHandle handle : handles) {
>             DropDownItem selectItem = (DropDownItem)
> statefulKnowledgeSession.getObject(handle);
>             ...
>
> I think I cannot be sure about the order the objects are retrieved (it's a
> collection, no guaranteed sorting!). So, I sort the DropDownItems
> alphabetically by their value.
>
> My question now is, as stated above: How can I implement a counter which I
> can use in the facts being inserted to keep my inserted facts
> (DropDownItems) in the same order as they are inserted?
>
> Thanks in advance
> Dominik
>
> …………………………………………………………………
> mit freundlichen Grüßen / kind regards
> Dominik Sandjaja
> Fon: +49 (0) 203 60878 183
> Fax: +49 (0) 203 60878 222
> e-mail: dominik.sandjaja at it-motive.de
>
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