New Action - Create if not found and do nothing if found

In some cases, for example, when you have import problems (items skipped), it is difficult to identify and select which rows still need to be imported. A possible solution could be the creation of an "Action" that does not append or update the existing ones, only add the new items if the identifier is not in omeka. The idea is very simple:

 If omeka_id != row_csv_id:
----add_item(row)