Rule Engine Variable

[Raphael_Klein]

Hello,
I would like to use the Rule Engine Variable as described here:

How to use properly the if switch node

Hello, I have a worgflow that is can be run according to 3 different case. For example, if the number of rows in a column is lower than 5, the workflow 1 should run. If the number of rows is between 6 and 30, the workflow 2 should run. If the number of rows is higher than 31, the workflow 3 should run. I tried to use case switch as follow but doesnt seem to work: [image] Thanks,

I am failing in defining the rules, as I am not into the expressions.
It should be:
If column “molecules” exist => 0
else => 1

0 and 1 should be index values that tells CASE Switch Data (Start) what to do.

Thanks for your help.

[armingrudd]

Hi @Raphael_Klein and welcome to the KNIME community forum,

To check whether a column exists or not, you can follow these steps:

1. Use the Extract Column Header node

2. Aggregate headers as a list by using the Column Aggregator node

3. Check if the column exists in the list and create the port value in the Column Expressions node using this expression:

if(arrayContains(column("List"), "molecules")) "top"
else "bottom"

Here is an example workflow:
26320-1-1.knwf (13.9 KB)

[Raphael_Klein]

Hei @armingrudd thanks for the welcome and your help.
It works like that.