multiInstanceLoopCharacteristics with an empty list

[harry11]

Hello,

I'm using a multiInstanceLoopCharacteristics with a List in my Activiti process. It works fine, except when the list is empty (the list is not null, it's just empty).
When the list is empty I have this error :

19 mai 2011 16:42:14 org.activiti.engine.impl.interceptor.CommandContext close
GRAVE: Error while closing command context
org.activiti.engine.ActivitiException: Invalid number of instances: must be positive integer value, but was 0
 at org.activiti.engine.impl.bpmn.behavior.ParallelMultiInstanceBehavior.createInstances(ParallelMultiInstanceBehavior.java:42)
 at org.activiti.engine.impl.bpmn.behavior.MultiInstanceActivityBehavior.execute(MultiInstanceActivityBehavior.java:82)
 at org.activiti.engine.impl.pvm.runtime.AtomicOperationActivityExecute.execute(AtomicOperationActivityExecute.java:40)
 at org.activiti.engine.impl.interceptor.CommandContext.performOperation(CommandContext.java:76)
…
‍‍‍‍‍‍‍‍‍

I think it should work when there is no instance in the list (and just skip the loop), shouldn't it ?

Regards,

[ronald_van_kuij]

(my bad)

You can't know everything, believe me…… I've tried…. for several hundered years now…

[frederikherema1]

You can't know everything, believe me…… I've tried…. for several hundered years now…

ROFL

[p4w3l]

It is annoying having extra gateway to test collection emptiness. If you see no reason to restrict empty collections maybe they could be allowed?

[melentye]

I second that, if it doesn't violate the BPMN2 spec or any other standards, it would be more convenient to skip for-each loops on empty collections without using an additional gateway

[ronald_van_kuij]

Fastest way to get this fixed is to fork the code on github, createva patch, add a testcase and make sure all other tests still run fine. Then createva pull request et voila…

[dromie]

Hi,

I ran into the same situation, and I've made the modification as well.
Here you go: https://github.com/Activiti/Activiti/pull/364
Should I also raise a Jira ticket for this?

Cheers,
dromie

[guillaume1]

Hi,

What is the status of this request ?
Is it already included in latest version of Activiti ? Is it planned to include it ?

We have a lots of cases where the multi instance collection is generated dynamically and empty lists are a valid result from the service point of view.

Cheers,
Guillaume.

[martin_grofcik]

Hi,

yes it is supported since September 2014. e.g org.activiti.engine.test.bpmn.multiinstance.MultiInstanceTest#testSequentialEmptyCollection
Regards
Martin