Generally the advice when using drools is that if you are wanting to use an array (or other type of collection) then you should probably be normalising your
data and putting the values of the collection into the working memory as their own object (pretend that drools is a relational database and follow the same rules as you would defining database tables and rows). Sometimes you can’t do this because of constraints
on the environment you are work within but in your case you I think you have two options:
Each room conceptually has its own sprinkler therefore each Sprinkler object contains a single room field.
If a Sprinkler has the concept of operating over multiple rooms then have a Sprinkler object containing its ID and status, then have multiple SprinklerHeadLocation
objects containing a reference to the Sprinkler and a single room each.
Rule “ if fire in room start sprinkler if room has sprinkler”
No-loop true
when
Fire($room : room)
SprinklerHeadLocation(room == $room, $sprinklerId : sprinklerId)
$sprinkler : Sprinkler(sprinklerId == $sprinklerId, status == false)??
then
modify($sprinkler){
setStatus(true)
};
End
Thomas
From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org]
On Behalf Of Esteban Aliverti
Sent: 09 June 2010 20:28
To: Rules Users List
Subject: Re: [rules-users] depicting array in rules
One way could be:
when
Fire($room : room)
$sprinkler : Sprinkler(room contains $room)
Room (this == $room, someField == "SomeValue")
then
modify($sprinkler){
setStatus(true)
};
End
If you dont have the Room as a Fact Type, then:
when
Fire($room : room)
$sprinkler : Sprinkler(room contains $room)
Room (someField == "SomeValue")from $room
then
modify($sprinkler){
setStatus(true)
};
End
I'm not 100% sure about this, but at least you can start from here
Best
2010/6/9 Fnu Mahalakshmi <FMahalakshmi@nyx.com>
Hi,
Is there any way I can represent an array of values in my rules??
I want to do this:
Fire{
Room,
Status}
Sprinkler{
Object [] Room = new Room[]{new Room(),new room()}
Status
}
Room{
Name,
Number}
Rule “ if fire in room start sprinkler if room has sprinkler”
No-loop true
when
Fire($room : room)
$sprinkler : Sprinkler( room == $room) # how can I search through the array of room values here???????
then
modify($sprinkler){
setStatus(true)
};
End
Any Idea if that is possible to implement in rules???
I could do it with adding different instances of sprinkler and rooms. But I want to minimize the amount
of repetition in data stored and loaded into the working memory.
Any idea??
Thank you,
M
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