Default Image Source vs Dynamic Image Source

Hi there,
(sorry in advance if I don’t explain myself properly, english is not my first language)

I’m kinda a newbie on Wappler, and I have this task now:

I want to show a default image (user avatar) if there’s a ‘null’ on a DBquery that I do, but if in the field of the table that I search in there’s content (url image) then I show that output from the server action.

I do understand that the dynamic attribute does this for me, but don’t really know how to formulate the if statement in there.

Thanks in advance!