[jboss-jira] [JBoss JIRA] Commented: (JBRULES-546) Please implement "collect( ... ) from" functionality
[ http://jira.jboss.com/jira/browse/JBRULES-546?page=comments#action_12367113 ]
Edson Tirelli commented on JBRULES-546:
---------------------------------------
From chaining (or maybe should be best to call it "nesting")
is done. Fernando is fixing the XML parser/dumper and we should be done.
In DRL it is like:
rule "Accumulate with From Chaining" salience 80
when
$cheesery : Cheesery()
$person : Person( $likes : likes )
$list : List( size > 2 )
from accumulate( $cheese : Cheese( type == $likes ) from
$cheesery.getCheeses(),
init( List l = new ArrayList(); ),
action( l.add( $cheese ); )
result( l ) )
then
results.add( $list );
end
rule "test collect with nested from"
when
$cheesery : Cheesery()
$person : Person( $likes : likes )
$list : ArrayList() from collect( Cheese( type == $likes ) from $cheesery.getCheeses()
)
then
results.add( $list );
end
You can nest any levels of from/collect/accumulate inside an accumulate/collect element,
but I don't see any real use for more than 1 level of nesting.
Please implement "collect( ... ) from" functionality
----------------------------------------------------
Key: JBRULES-546
URL: http://jira.jboss.com/jira/browse/JBRULES-546
Project: JBoss Rules
Issue Type: Feature Request
Security Level: Public(Everyone can see)
Reporter: Dirk Bergstrom
Assigned To: Edson Tirelli
I need to count the number of sub-objects that meet various criteria. As an example,
suppose I have several hundred Town objects, each of which has a list of perhaps a few
hundred Person objects. I need to write rules like:
"Find all the towns that have more than three disabled people with incomes over
$100K."
"For each town with more than 1000 residents that has more than 50 poor children
under the age of 8, add a teacher for every 25 children."
I'm shaky on JBR syntax, but I think those would translate to something like:
rule "disabled"
when
ArrayList(size > 50) from collect( Person( disabled == "yes", income
> 100000 ) from town.getPersons() )
then
//do stuff
end
rule "teachers"
when
town : Town( population > 1000 )
count : Arraylist from collect( Person( disabled == "yes", income >
100000 ) from town.getPersons() )
count( size > 50 )
then
town.addTeachers(count.size() / 25)
end
(I'm not really working with towns and people, but it makes for easily understood
examples)
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