Force a column to be integer wghen iteratively using Excel files

Experts, I would like to read several Excel files. One column holds ineger values for some of the Excel Sheets and is empty for other Excel sheets. The empty column is read in as string, so my worrflow fails when appending the files with different formats. Is there any way to force empty columns to be read in as integers?

Attached is a reproducible example.

Thanks, Max
FILE_READER_EXAMPLE.knwf.knar (54.4 KB)

Hi there!

Your workflow doesn’t even work when you add numbers in Col0 to Excel File2.
Error I get at Excel reader node: Execute failed: Your InputStream was neither an OLE2 stream, nor an OOXML stream.

Do not believe you can force empty columns to be read as Integers.

What you can do (with assumption you get rid of above Error) is to create a new column from Col0 which will be an Integer column. If in Col0 was a missing value then assign some Int value (0 I guess) and otherwise write in it real value. Drop Col0 afterwards. Then You can use Math node on new column. For this you will have to use 2 times Rule engine node…