Order models by a property or custom field in Django Rest Framework-CodePudding

Am having this kind of a Model, and I wanted to order by blog_views property, how best can this be done.

This is the model :

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()

I read about annotate but couldn't get a clear picture, how can I formulate this in my view.

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'
                     ]

I want to filter by a property in the URL

CodePudding user response：

You can't order by a method field because the ordering is done at the database level, and the database has no idea that, that field exists.

But you can use annotate like so:

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')

If you want the ordering to be optional you can use 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