Help updating a table within a loop

[lauren_ames]

Hi all, I’m trying to build a workflow that takes a list of needed test compounds and matches to a list of compounds in our physical inventory.
Input is a list of needed compounds in the “Cherrypick” Excel file (with headers Compound Name, Batch and Concentration). For each compound in this list, I need to find an exact match in our inventory list - this is the “available aliquot” Excel file (headers Compound Name, Batch, Concentration, ID and Position). So far I’ve used a Chunk loop start set to 1 row per chunk to iterate through my “cherrypick” file followed by a join function with join columns Compound Name, Batch and Concentration.
Since there are multiple matches in our inventory, I used row filter to select the first result. The selected aliquot then needs to be removed from the “available aliquot” list so that it can’t be selected again in later iterations through my “cherrypick file”. I’ve set this up using the row filter function, and it works for the first iteration of the loop but not the subsequent ones.
Can anyone see where I’ve gone wrong and why my “available aliquot” table isn’t being updated within the loop? Any advice would be appreciated!

[k10shetty1]

Hello @lauren_ames ,

Welcome to the KNIME Forum!

Since the Excel Reader node reading the available aliquot file is not connected to the Chunk Loop Start node, it is not executed again during the subsequent iteration. To execute again I recommend connecting the flow variable from the Chunk loop start node to the Excel reader node.

Also to keep the loop closed, connect the flow variable from the Excel writer to the Chunk Loop End node.

I hope this resolves the issue.

Best,
Keerthan