python之在 Django 中使用案例

我正在尝试根据博主的总数显示值 A、B、C 或 D。但我收到错误 - 无法将关键字“总计”解析为字段。有人可以建议正确的方法吗？谢谢

模型.py

class Blog(models.Model): 
 
     author = models.ForeignKey(User, on_delete = models.CASCADE, related_name='blogs')  
     likes  = models.ManyToManyField(User, blank=True, related_name='blog_likes') 
     title = models.CharField(max_length=100) 
 
     def total_likes_received(user): 
          return user.blogs.aggregate(total_likes=Count('likes'))['total_likes'] or 0 
 
     @property 
     def total(self): 
         return count(self.author.title) + count(self.author.likes) 

View .py

def get_queryset(self): 
    return (Blog.objects.filter(date__lte=timezone.now()) 
                                    .order_by('date') 
                                    .annotate( 
                name=Case( 
                      When(total__gt=0,total__lte=11, then=Value('B')), 
                      When(total__gt=10,total__lte=21, then=Value('C')), 
                      When(total__gt=20,total__lte=31, then=Value('D')), 
                      default=Value('A'), 
                      output_field=CharField(), 
                         ), 
                                              ).values_list('name') 
            ) 

请您参考如下方法:

您还必须使用 Django F()和 Count() 注释函数...
试试下面的代码:

Blog.objects.annotate( 
    author_titles=Count('author__title'), 
    author_likes=Count('author__likes') 
).annotate( 
    total=F('author_titles') + F('author_likes') 
).annotate( 
    name=Case( 
        When(total__gt=0,total__lt=11, then=Value('B')), 
        When(total__gt=10,total__lt=21, then=Value('C')), 
        When(total__gt=20,total__lt=31, then=Value('D')), 
        default=Value('A'), 
        output_field=CharField(), 
    ) 
)