Method delete

src/polymorphic/models.py:242–274

Behaves the same as Django's default :meth:`~django.db.models.Model.delete()`, but with support for upcasting when ``keep_parents`` is True. When keeping parents (upcasting the row) the ``polymorphic_ctype`` fields of the parent rows are updated accordingly in a tran

(
        self, using: str | None = None, keep_parents: bool = False
    )

        return self.__class__.objects.db_manager(self._state.db).get(pk=self.pk)

    def delete(
        self, using: str | None = None, keep_parents: bool = False
    ) -> tuple[int, dict[str, int]]:
        """
        Behaves the same as Django's default :meth:`~django.db.models.Model.delete()`,
        but with support for upcasting when ``keep_parents`` is True. When keeping
        parents (upcasting the row) the ``polymorphic_ctype`` fields of the parent rows
        are updated accordingly in a transaction with the child row deletion.
        """
        # if we are keeping parents, we must first determine which polymorphic_ctypes we
        # need to update
        parent_updates = (
            [
                (parent_model, getattr(self, parent_field.get_attname()))  # type: ignore[union-attr]
                for parent_model, parent_field in self._meta.parents.items()
                if issubclass(parent_model, PolymorphicModel)
            ]
            if keep_parents
            else []
        )
        if parent_updates:
            with transaction.atomic(using=using):
                # If keeping the parents (upcasting) we need to update the relevant
                # content types for all parent inheritance paths.
                ret = super().delete(using=using, keep_parents=keep_parents)
                for parent_model, pk in parent_updates:
                    parent_model.objects.db_manager(using=using).non_polymorphic().filter(
                        pk=pk
                    ).update(
                        polymorphic_ctype=lazy_ctype(parent_model, using=using or DEFAULT_DB_ALIAS)
                    )
                return ret
        return super().delete(using=using, keep_parents=keep_parents)

    delete.alters_data = True  # type: ignore[attr-defined]