Group By with Flow Variables and NO grouping column


I’m attempting to learn how to use the GroupBy node with flow variables. Within my process however I do not need to group on a field, I just need to get the sum of each column. I’ve attached a sample workflow demonstrating my issue.
Group By Flow Variable.knwf (32.9 KB)

I’ve configured the flow variable section as such:

But when clicking apply it says “Invalid settings: please select at least one group column or aggregation option”.

I played around with the sample workflow from this thread Using Flow Variables with GroupBy – KNIME Community Hub

I mirrored the same process except for adding a group variable. It seems like I have to manually add the aggregation columns even though they are supposed to be controlled by flow variables.

Hoping to get some help or suggestions.

Thanks, John

You are right. In many cases you always have to fill in something in order to actually get the node working. That can be anything since it will be overridden by the flow variables anyway. In this case, the array size matters so the number of columns in the node and in the stringList have to be same.

Here it’s still taking the sum based on the flow variable.

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I see. Thank you for your help!

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