[rules-users] Drools ruturn multiple results based on child objects data length

[Vikrant Yagnick]

My feeling after reading this post is that you need to execute a rule, if some child object exists.
I suggest using the Exists Feature in Drools for doing something like that.

It would be the same thing if you are writing SQL. If you join a Master Table with child tables you will get as many records as there are child records for each master record.

However, if you only want one master record if there are child record, you would need to use the exists statement.

Example:


rule "Multiple results set"
when

    order: Order
    exists ( Invoice from order.invoices)

  then

    System.out.println("Rule Example (Multiple results set)"+order.getId());
end;


Cheers,
Vikrant

From: rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Mohamed Riyaz
Sent: Monday, September 08, 2008 12:05 PM
To: rules-users at lists.jboss.org
Subject: [rules-users] Drools ruturn multiple results based on child objects data length


Hi,

In one-to-many relationship object type, Drools generate multiple results based on child objects data length. ie. No of child records
belongs to parent object. I wanted the RHS part should be executed only if conditions imposed
on child object satisfies.

I have two facts with 1-* relationship defined in object mapping.

class Invoice{}

class Order{

private Set<Invoice> invoices;

}

I wanted RHS should be executed with only one result  irrespective of child records length.

rule "Multiple results set"
when

    order: Order()
    invoice : Invoice() from order.invoices


  then

    System.out.println("Rule Example (Multiple results set)"+order.getId());
end;

Result:
 Rule Example (Multiple results set)1000
 Rule Example (Multiple results set)1000

Please help me in resolving this issue.

Regards,
Riyaz



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