revisions.py 文件源码

def get_deleted(self, model_class, db=None, model_db=None):
        """
        Returns all the deleted versions for the given model class.

        The results are returned with the most recent versions first.
        """
        db = db or DEFAULT_DB_ALIAS
        model_db = model_db or db
        content_type = ContentType.objects.db_manager(db).get_for_model(model_class)
        live_pk_queryset = model_class._default_manager.db_manager(model_db).all().values_list("pk", flat=True)
        versioned_objs = self._get_versions(db).filter(
            content_type = content_type,
        )
        if has_int_pk(model_class):
            # If the model and version data are in different databases, decouple the queries.
            if model_db != db:
                live_pk_queryset = list(live_pk_queryset.iterator())
            # We can do this as a fast, in-database join.
            deleted_version_pks = versioned_objs.exclude(
                object_id_int__in = live_pk_queryset
            ).values_list("object_id_int")
        else:
            # This join has to be done as two separate queries.
            deleted_version_pks = versioned_objs.exclude(
                object_id__in = list(live_pk_queryset.iterator())
            ).values_list("object_id")
        deleted_version_pks = deleted_version_pks.exclude(
            type = VERSION_DELETE,
        ).annotate(
            latest_pk = Max("pk")
        ).values_list("latest_pk", flat=True)
        # HACK: MySQL deals extremely badly with this as a subquery, and can hang infinitely.
        # TODO: If a version is identified where this bug no longer applies, we can add a version specifier.
        if connection.vendor == "mysql":
            deleted_version_pks = list(deleted_version_pks)
        # Return the deleted versions!
        return self._get_versions(db).filter(pk__in=deleted_version_pks).order_by("-pk")

    # Signal receivers.