"""A list of columns to show in the Edit form.
        This dynamically calculates additional fields from providers and add
        them to the backing list. This calculation is done exactly once (by
        checking we're referencing the class-level variable instead of the
        instance-level), and only after we enter the request context (to skip
        superfuluous checks done by Flask-Appbuilder on startup).
        """
        if self._edit_columns is type(self)._edit_columns and has_request_context():
            self._edit_columns = [
                *self._edit_columns,
                *(k for k, _, _ in self._iter_extra_field_names_and_sensitivity()),
            ]
        return self._edit_columns
    @action("muldelete", "Delete", "Are you sure you want to delete selected records?", single=False)
    @auth.has_access(
        [
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_DAG),
        ]
    )
    def action_muldelete(self, items):