How to map empty input in Flowable DMN table

Hi Team,

I have modelled a DMN and added it as reference to a decision task. My DMN receives form variable as input and sets output based on the value in this particular form variable.

This form field is not a mandatory one. so I am getting this issue when the form filed is empty.
‘DMN decision with key rule_Evaluation execution failed. Cause: Unknown property used in expression: #{attachment_type == “Approval-CFO”}’

Could you please help

That exception means the attachment_type isn’t set. the easiest would be to set a value (even the empty string) to that variable just before the DMN table invocation.

hi @joram
Thanks for the response.
But this decision task is added directly after the start event. The attachment type form field is not mandatory and user can leave it blank. So do we need to add any custom logic somewhere (after start event or before decision task) to set this variable empty when it is not passed?
Is there any other way to handle this through DMN?

Hi Pushkala,
You could simply add an execution listener to the start event.
The listener would simply set the variable.
e.g. ${empty execution.getVariable(“bar”)?execution.setVariable(“bar”,“”):null}

Here we test for foo (the attachment variable), if empty the set to empty string.