Cache and provide in-memory fallback

    @property

    def elements_deleted(self):

        if not hasattr(self, "_elements_deleted"):

            if session := object_session(self):

                stmt = self._build_nested_collection_attributes_stmt(

                    hda_attributes=("deleted",), dataset_attributes=("deleted",)

                )

        stmt = exists(stmt).where(or_(HistoryDatasetAssociation.deleted == true(), Dataset.deleted == true()))

        return object_session(self).execute(select(stmt)).scalar()

                stmt = stmt.exists().where(or_(HistoryDatasetAssociation.deleted == true(), Dataset.deleted == true()))

                self._elements_deleted = session.execute(select(stmt)).scalar()

            else:

                self._elements_deleted = False

                for dataset_instance in self.dataset_instances:

                    if dataset_instance.deleted or dataset_instance.dataset.deleted:

                        self._elements_deleted = True

                        break

        return self._elements_deleted

    @property

    def dataset_states_and_extensions_summary(self):