Unwanted selection when using expression in Multi Box

[#1]

I have a problem when filtering my Multi Box to only show the dates for which I have data in a specific field. The expression I am using is this:

=if( not IsNull([Värde SO-historik]), Datum )

The result is what I want - now only the relevant dates are shown:

However, when selecting a date I also get a selection in the field I used in the above condition:

This is undesirable. How can I make it so that no selection is made in the field "Värde SO-historik"?

[swuehl]

The easiest way would be to create another field with the same filter in your data model, then use this field in the multi-box.

[#3]

Hi, thanks for the prompt answer!

This is actually how I have currently solved it, but I wanted to use the field "datum" so that a selection here will be meaningful also for other tabs and charts in my app (it is quite big with 9 tabs - one for each KPI - and the specified field should optimally be relevant for all the tabs).

[swuehl]

Try something like

=aggr( if( not only({1} IsNull([Värde SO-historik])), only({1}Datum) ), Datum)