Empty value conditions

I got trouble setting “if empty value” conditions in both AC and SC.

In app connect for example, I want to show an element using a dynamic attribute only when a certain database field (checked with data binding) is empty or has an empty value or string. I can’t get that to work using operations like bound_field_value!="",bound_field_value!=null, etc. What’s the right way to achieve this?

Secondly, in a serverconnect script I want to check if a dropzone/upload field input value is not empty as a condition for steps to be executed. The condition value I set is $_POST.upload_image, but it seems not to work. Also tried $_POST.upload_image.name, but that also doesn’t work.

Thanks for any help with this.