Currently we have requirement to add restrictions to DAM Asset Upload which checks file type, size and file content using for 3rd party API. We do this in DAM Update Asset Workflow by adding a custom step.
Currently we are stuck at a place where in case when file is not allowed, we are not able to show alert on UI to authors with some message. I see that "DAM Asset Upload Restriction" configuration has a nice alert saying upload failed. From what I checked that calls a servlet which returns error and then this alert is shown.
Is there a way we can do the same for our custom restrictions. If workflow is the best way for that or if we can have another way of doing it which is more user friendly.