[rules-users] Avoid propagation of update in a then block.

[Patrik Dufresne]

Hi Mike,

I see your point, it's very valid for the snippet rule, but can't be apply
to the real one since I need to run a function using eval().

Patrik Dufresne


On Tue, Mar 13, 2012 at 4:45 PM, Mike Melton <mike.melton at gmail.com> wrote:

> Let the rule engine do what it does best. You are fighting against the
> optimizations of the engine by trying to control the flow. You can rewrite
> your rule as
>
> rule "my-rule"
>  when
>   $entity : Entity( closed == false )
>  then
>   modify($entity) { setClosed(true); }
> end
>
> The rule will fire (once) for each Entity which matches the condition. I
> haven't taken the time to apply the same exercise to your more complex
> rule, but a general rule you should abide by is "No looping in the
> consequence unless I have a really good reason."
>
> Mike
>
>
> 2012/3/13 Patrik Dufresne <ikus060 at gmail.com>
>
>> Hi,
>>
>> I have some trouble to figure out how to stop / start the propagation of
>> updates within a Then block.
>> Here is a snippet to represent the problem I have.
>>
>> rule "my-rule"
>>     when
>>         $objects : List()
>>                 from accumulate( $entity : Entity(closed==false),
>> collectList($entity) )
>>     then
>>         for(Object obj : $objects) {
>>             ((Entity) obj).setClosed(true);
>>             update(obj);
>>         }
>> end
>>
>> When this rule's consequence is called first, the first enity in the list
>> is 'update', but then update if propagated to immediately causing the rule
>> to be evaluated with all the entities minus the updated one. So I'm
>> wondering if there is a transaction like operation allowing me to update
>> all the entities in the list and then fire the rules.
>>
>> According to the documentation no-loop should have help me for this.
>>
>> Here is the original rules
>> rule "close-shift"
>> salience -1
>>  when
>> $shift : Shift( )
>> $assignments : List( size > 0 )
>>  from accumulate (
>> $assignment : PlanifEventAssignment(
>> close == false,
>>  shift == $shift ),
>> collectList($assignment) )
>> $availables : List( size >= $assignments.size )
>>  from accumulate ( ( and
>> ShiftAssignment(
>> shift == $shift,
>>  $employee : employee)
>> $available : EmployeeAvailable (
>> employee == $employee,
>>  assignment.shift == $shift) ),
>> collectList($available) )
>> eval( Dfs.search($assignments, $availables) != null )
>>  then
>> // Recalculate the result.
>> Map table = Dfs.search($assignments, $availables);
>>  for(Object entry : table.entrySet()) {
>> PlanifEventAssignment assignment =
>> (PlanifEventAssignment)((Entry)entry).getKey();
>>  EmployeeValue employee = (EmployeeValue)((Entry)entry).getValue();
>> assignment.setClose(true);
>>  assignment.setEmployee(employee);
>> update(assignment);
>> }
>> end
>>
>>
>> Patrik Dufresne
>>
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>>
>>
>
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