Facts are simply POJO's so you can only achieve in a rule
that you could in Java.
I assume (given the presumably simplified example below)
that you have a super class Shape and subclasses Rectangle and Cube that extend
Shape.
Therefore I think your separate "twodimensional" and
"threedimensional" rules should reference the subclasses and not the super class
(as a call to Shape.getVolume() would fail in Java).
I don't think Drools performs subclass conversion on LHS
patterns!?!?!
Hi,
I am using agenda groups to pick sets of
rules to fire based on an attribute value. The presence or absence of other
attributes is dependent on the value of this attribute based on which I
select a particular agenda group.
Here is an example
rule
"ABC"
when
Shape( type = "rectangle"
)
then
drools.setFocus("twodimensional")
end
rule "PQR"
when
Shape( type = "cube" )
then
drools.setFocus("threedimensional")
end
rule
"area threshold"
agenda-group "twodimensional"
when
Shape( area > 20 )
then
System.out.println ("large object"
);
end
rule "volume threshold"
agenda-group
"threedimensional"
when
Shape( volume
> 20 )
then
System.out.println
("large object" );
end
Suppose if my shape object is a
rectangle, then it wouldnt have the volume attribute. In this case when we try
to run these rules it would throw a NoSuchElementException.
Is
there a way to avoid this? Agenda groups help us fire the RHSs conditionally,
Is there a way by which I can conditionally fire LHS of certain sets of rules
?
Thanks
Jai