How to use Lookup in an existing row

[bouhme]

Hey there,
i use lookup to copy the contend from a cell in a nother table to the row i´m creating.

I do this with : LOOKUP([_THISROW].[LeistungsArt], “Materiallisten”, “LeistungsArt”, “LeistungsText”) in the initial value expression
(thanks to Steve Coile)

But sometimes i have to do this in an existing row.
Is it possible to do LOOKUP with a clickable action to do this in a existing row?

[Steve]

Absolutely! Create an action of type Data: set the value of a column with a To this value of the one you’ve given above.

[bouhme]

Great. You are my hero.
It works.

With the condition in Behavior “only if this condition is true” and this expression:
AND(ISNOTBLANK([LeistungsArt]), ISBLANK([LeistungsText]))

It only appears when I need it and there is no error message about empty cell