[rules-users] null checking

[David Sinclair]

read the manual

http://downloads.jboss.com/drools/docs/4.0.7.19894.GA/html_single/index.html

On Thu, Oct 16, 2008 at 3:03 PM, samd <sdoyle_2 at yahoo.com> wrote:

>
>
>
> samd wrote:
> >
> > How do I evaluate null conditions in the following case for example?
> >
> > seller: ( seller.cheese != null && seller.active == true )
> > cheese: ( cheese.type == "chedder" ) from seller.cheese
> >
> > In the above example seller.cheese is null but seller is used in the
> > second part of the rule since we can't evaluate facts for null for some
> > reason how do you check for a null condition.
> >
> >
>
> should be cheese: ( type == "chedder" ) from seller.cheese
>
> anyways I tried doing this
>
> (
>  seller: ( seller.cheese != null && seller.active == true )
>  cheese: ( cheese.type == "chedder" ) from seller.cheese
> )
> or
> (
>  seller: ( seller.cheese = null && seller.active == true )
> )
> Which throws an error
> I just need the correct syntax I guess heh
>
> --
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> http://www.nabble.com/null-checking-tp20015953p20016182.html
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>
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