Allow each action to decide default value for select_across
|Reported by:||Owned by:||nobody|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
It seems the "select_across" option in Admin actions is under-utilised [e.g. not at all].
It would allow an action to not require any selected items, instead operating on all matching the current filter spec.
However, because of a duplicate check it never gets the chance.
The attached patch removes the check, changes select_across to NullBooleanField, with Null as default, and will set it to the select_across property of the selected action if it has one, or False otherwise.