models.py 文件源码

def update_tags(self, obj, tag_names):
        """
        Update tags associated with an object.
        """
        ctype = ContentType.objects.get_for_model(obj)
        current_tags = list(self.filter(items__content_type__pk=ctype.pk,
                                        items__object_id=obj.pk))
        updated_tag_names = parse_tag_input(tag_names)
        if settings.FORCE_LOWERCASE_TAGS:
            updated_tag_names = [t.lower() for t in updated_tag_names]

        # Remove tags which no longer apply
        tags_for_removal = [tag for tag in current_tags \
                            if tag.name not in updated_tag_names]
        if len(tags_for_removal):
            TaggedItem._default_manager.filter(content_type__pk=ctype.pk,
                                               object_id=obj.pk,
                                               tag__in=tags_for_removal).delete()
        # Add new tags
        current_tag_names = [tag.name for tag in current_tags]
        for tag_name in updated_tag_names:
            if tag_name not in current_tag_names:
                tag, created = self.get_or_create(name=tag_name)
                TaggedItem._default_manager.create(tag=tag, object=obj)