Iteratively processing rows in Webportal



I would like to process and annotate iteratively rows in a table within the webportal. My table contains 10-50 entries with chemical structures, and each row should be displayed one at a time, with a drop-down or radio button Single selection node which requires an input from the user/scientist. This input is then merged with the particular row as an additional column.
My current prototype looks like this:

And my current implementation of the workflow looks like this:
with the wrapped metanode containing the following nodes:

(I implemented this with a recursive loop, in analogy to the workflow depicted in this blog post, but I tried also with a standard loop)
If I execute the Recursive Loop End node in KNIME, the workflow runs through all rows, but does not open the interactive Table View within the metanode. If I use stepwise execution of the loop, the Table View opens, and I can make the selection with the radio buttons. For the first row, the selection is then merged with the corresponding row, but for the next rows (after stepping through the loop), the selection is not stored and I get the following message: “ERROR AbstractWizardNodeView Could not set error message or trigger re-execution: Can’t reset wrapped metanode - some downstream nodes are still executing”

What am I missing ?

Alternatively, is there a way to include the drop-down/radio button selection with the row itself? I would then skip the loop and have the user do the selection within one single table view (each row individually).

Thanks in advance




Hi Serge,

have you checked the configuration of the nodes from the blog post you mentioned or have you used only the pictures to rebuild it?
If you could share your workflow that would be great so I could look into your settings!

Regarding your last question - I don’t think its possible to do it but I will check if there is a workaround!




I have tried this out on my own now, was just too curious…

Have you tried the Chunk loop?
It worked for me at least. Please find the example attached. If you deploy it to the server it should work.

ChunkLoopExample.knar (50.1 KB)



Hi Martyna,

Thanks a lot for the example. It works in the webportal, as intended. I could get mine to work too in the webportal. My reasoning on how things should work was correct (both with a Chunk start loop and a recurring loop), but it seems you cannot “simulate” such a iterative behavior within KNIME itself.

Best regards