Trying to do validation on dropdown copy/paste in DataTable

I have a DataTable that allows users to copy/paste rows into it. There are a series of dropdown values associated with this DataTable. I found an issue that when a user copy/paste values into the DataTable, it allows the user to past in values that don’t match the drop downs. It won’t be displayed in the data table but once they save it, the wrong value will be submitted.

Is there a way to use validation to fill in a value if they try to paste in a value that doesn’t match the dropdown? I’m trying to use on_change and validation but it doesn’t seem to be doing anything. I may not be doing this correctly. Please advise.

this is a dropdown for currency. If they try to paste in a currency that isn’t supported, I want to reject that paste and fill in a string like “Error” or just replace the wrong value with null or blank.

                   {'id': 'currency', 'name': 'Currency', 'type': 'text',
                         'presentation': 'dropdown', 'on_change': {
                             'action': 'validate', 'failure': 'default'
                         }, 'validation': {'default': 'error'}},