Unable to parse "1" as boolean expression

Hi guys,
I’m trying to use a variable coming from the Boolean Input node (currently “1”) to set a boolean flow variable of a wrapped metanode. In practice I have a wrapped metanode inside another wrapped metanode. The problem is that with the variable given by the Boolean Input node (of the external metanode) I cannot set another Boolean Input node (of the internal wrapped metanode). I my opinion this is rather incoherent. Do I miss something? Do you have a solution or workaround for it?
Thanks in advance

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I think that there’s just no “boolean” type for flow variables in KNIME. I was also surprised when I discovered that (probably that has changed in recent versions and I’m just not up-to-date though?!).

– Philipp

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Hi there,

there are 3 types of flow variables in KNIME: double, integer and string. All Boolean nodes - Configuration, Widget and Input output integer flow variable with value 0 or 1. Now, to override any configuration in any node that is Boolean (true or false, one or zero, checked or unchecked - for example check box in File Reader node read row IDs) flow variable should be of type string with value true or false.

I’m aware this is not straightforward and had problems with it myself but believe some improvements are coming in this area.


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Indeed there are improvements coming - we’re working on adding some new types for flow variables, including boolean and arrays. No ETA yet, but it’s in active development. :slight_smile:


Perfect. Thank you everybody for the info!

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