在 Django Rest Framework 中按属性或自定义字段对模型进行排序

Question

我有这种型号，我想通过blog_views 属性订购，如何才能做到最好。

这是模型：

class Post(TimeStampedModel, models.Model):
    """Post model."""
    title = models.CharField(_('Title'), max_length=100, blank=False,
                             null=False)
    # TODO: Add image upload.
    image = models.ImageField(_('Image'), upload_to='blog_images', null=True,
                              max_length=900)
    body = models.TextField(_('Body'), blank=False)
    description = models.CharField(_('Description'), max_length=400,
                                   blank=True, null=True)
    slug = models.SlugField(default=uuid.uuid4(), unique=True, max_length=100)
    owner = models.ForeignKey(User, related_name='posts',
                              on_delete=models.CASCADE)
    bookmarks = models.ManyToManyField(User, related_name='bookmarks',
                                       default=None, blank=True)
    address_views = models.ManyToManyField(CustomIPAddress,
                                           related_name='address_views',
                                           default=None, blank=True)
    likes = models.ManyToManyField(User, related_name='likes', default=None,
                                   blank=True,
                                   )

    class Meta:
        ordering = ['-created']

    def __str__(self):
        """
        Returns a string representation of the blog post.
        """
        return f'{self.title} {self.owner}'

    @property
    def blog_views(self):
        """Get blog post views."""
        return self.address_views.all().count()

我阅读了有关annotate 的信息，但无法获得清晰的图像，我该如何制定这一点。

class PostList(generics.ListCreateAPIView):
    """Blog post lists"""
    queryset = Post.objects.all()
    serializer_class = serializers.PostSerializer
    authentication_classes = (JWTAuthentication,)
    permission_classes = (PostsProtectOrReadOnly, IsMentorOnly)
    filter_backends = [filters.SearchFilter, filters.OrderingFilter]
    search_fields = ['title', 'body',
                     'tags__name', 'owner__email',
                     'owner__username'
                     ]

我想按 URL 中的属性进行过滤

Answer 1

您不能按方法字段排序，因为排序是在数据库级别完成的，而数据库不知道该字段存在。

但是你可以像这样使用annotate：

from django.db.models import Count


class PostList(generics.ListCreateAPIView):
    ...
    queryset = Post.objects.annotate(address_views_count=Count('address_views')).order_by('address_views_count')

如果您希望订购是可选的，您可以使用filter_queryset:

class PostList(generics.ListCreateAPIView):
    def filter_queryset(self, request, queryset, view):
        ordering = self.request.GET.get("ordering", None)
        if ordering == 'blog_views':
            queryset = queryset.annotate(address_views_count=Count('address_views')).order_by('address_views_count')

        return queryset