Recursive Loop problem: Execute failed: Runtime class of object does not comply with its supposed superclass String

[gcincilla]

Dear KNIMErs,
I found a problem while I was working with the Recursive Loop nodes and I suspect that it may be a bug. As you can see in the attached workflow (top branch of the component), the following error is triggered in the second iteration of the recursive loop:

ERROR Recursive Loop End 6:64:0:87 Execute failed: Runtime class of object "0" (index 2) in row "Row0#1" is Number (integer) and does not comply with its supposed superclass String

As I was suspecting that the problem was related with the “original_order” integer column, I’ve tried to convert it into a string (attached workflow: bottom branch of the component). In that case the error is not triggered but, as you can see in the loop end node, the content of “original_order” and “chembl_search_url” columns appear to be exchanged.

I’ve experienced this using KNIME 4.6.1. Any feedback is welcome.

superclass_string_compliance.knwf (338.4 KB)

[AlexanderFillbrunn]

Hi @gcincilla,
This problem occurs because in the second iteration the columns are sorted differently than in the first, causing a type incompatibility issue. You can fix this by simply adding a Column Resorter node to your Column Filter (the one with the caption “select cols to collect”).
Kind regards,
Alexander

[gcincilla]

Hi Alexander,
Thank you for your answer. I’m sorry, I didn’t realise that the order was different.
Thank you for the suggestion!
Best,
Gio