I gave setting that text field to 0 a try. It made no difference. I am using LogAttribute to log the attributes before and after the UpdateAttribute and the one before the UpdateAttribute never shows the attribute "theCount". The one after UpdateAttribute shows: FlowFile Attribute Map Content Key: 'filename' Value: '6904754831116' Key: 'theCount' Value: '' Key: 'path' Value: './' ... View more

Hi Brian, thanks for your reply. "Have you tried setting "Stateful Variables Initial Value" to 0 for the example?" I'm not sure how to do that. I would have expected the web UI to link to a tabular attribute-setting widget for the "Stateful Variables Initial Value" in the NiFi web UI but it takes a text value. Further its text field says "Supports expression language: false" so I don't see how to create a map or map entry using the text field. [I don't know what the expression language syntax would be for creating a map or adding an entry to a map even if it did. I tried various (made up) guesses, for example, ${theCount.set(0)} but not surprisingly it didn't work.] I'm sure I'm missing something but I haven't even been able to even find a template XML on the web that sets "Stateful Variables Initial Value" to see an example. ... View more