User Prompt to select multiple string values that can be used in a rule engine


Is there a way of prompting a user mid workflow (after a GroupBy node) to allow them to select multiple values from a column and then use the user selections in a rule based row filter?

For example, my GroupBy node gives me the following output:


I would like the user to be able to select multiple asset categories (from the table above) which will then go into a rule based row filter to extract the related records.

For example, if the user selected Asset Category A, B and C, the result from the rule based row filter would be a table of 42,504 assets with category A, B or C.


@Fostc80857 Could you provide the data in your post in a readable form rather than just a screenshot?

When you use the KNIME hub with widget nodes that should be possible
e.g. sth like that



Hi @Daniel_Weikert

The workflow is for my own personal use which I have created for internal auditing purposes.

What I would like to do is: at a certain point in the workflow be prompted to select from a list of asset categories which then become a variable that I can to filter and do further testing in the resulting table. Is this possible?

The reason for the selection list is that from period to period some categories can change so I would like to be able to select only the categories I am interested in when I carry out the test.

This is a snippet what I have created so far:

I have used the groupby to get a table of asset categories. I have then transposed, created a collection column (called "AggregatedValues) which I have then used as my possible choices flow variable in the selection widget.

Looking at your example workflow above I may not need to transpose and create a collection column?

The groupby created the collection column in my workflow.

Any chance of a screen shot(s) to show me the process as my groupby doesn’t appear to be doing the same. (Apologies, I am new to using variables and I am trying to get my head around them).

Also I am not sure what you mean by collection column.


A collection is just a list (or set) which you can create in the aggregation part
This can then be used as possible selection values
hope that helps

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Thanks @Daniel_Weikert

This is really helpful as I did not know this functionality within the GroupBy node existed, however, when I manually aggregate my asset category column I get the following warning message.

Am I missing something?

Also, going back to my initial query - will the Multiple Selection Widget open a dialog box for me to select from when the workflow is executed? Or, will I have to execute separately and open the view?

And, once I have made my selection and have my flow variable, how would I pass this into the rule based row filter?


Hi @rfeigel

If I have understood your request, it would just be a column of the Asset Category, so:


and so on.

I only require the user to select from the Asset Category column (so the Count column could be removed)


I have solved the issue and no longer get the error message. My groupby node was trying to create a list from the initial dataset (which was trying to put 200,000 entries in a list). I solved this by using a second groupby node to create the list.

Also, instead of passing the variable created in the multiple selection widget in to a rule-based row filter, I have used the reference row filter node which uses the selected value table created by the multiple selection widget.

Thanks for your help


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