如何返回最后的评论？

Question

我可能有一个小问题。即当我使用'post.cmets.all'时如何提取最后一条评论

class CommentPost(models.Model):
      user = models.ForeignKey(Profil, on_delete=models.CASCADE)
      post = models.ForeignKey(Posty, on_delete=models.CASCADE, related_name="comments")
      content1 = models.TextField(max_length=250, blank=False, null=False)
      date_posted = models.DateTimeField(default=timezone.now)
      date_updated = models.DateTimeField(auto_now=True)

def __str__(self):
    return str(self.content1)


class Posty(models.Model):
   title = models.CharField(max_length=250, blank=False, null=False, unique=True)
   sub_title = models.SlugField(max_length=250, blank=False, null=False, unique=True)
   content = models.TextField(max_length=250, blank=False, null=False)
   image = models.ImageField(default="avatar.png",upload_to="images", validators=[FileExtensionValidator(['png','jpg','jpeg'])])
   author = models.ForeignKey(Profil, on_delete=models.CASCADE)
   updated = models.DateTimeField(auto_now=True)
   published = models.DateTimeField(auto_now_add=True)
   T_or_F = models.BooleanField(default=False)
   likes = models.ManyToManyField(Profil, related_name='liked')
   unlikes = models.ManyToManyField(Profil, related_name='unlikes')
   created_tags = models.ForeignKey('Tags', blank=True, null=True, related_name='tagi', on_delete=models.CASCADE)

观看次数

    tag = request.GET.get('tag')
if tag == None:
    my_tag = Posty.objects.all
    print(my_tag)
else:
    my_tag = Posty.objects.filter(created_tags__tag=tag)
    print(my_tag)

如果我尝试使用 '[:1]' 或最后，这不起作用。

Answer 1

您可以通过以下方式获取最后一条评论：

post.comments<strong>.latest('date_posted')</strong>

或者如果您想要date_updated 的最新信息，请使用：

post.comments<strong>.latest('date_updated')</strong>

如果您想获取每个帖子的最后一条评论，您可以使用Prefetch 对象：

from django.db.models import OuterRef, Subquery

posts = Posty.objects.annotate(
    latest_comment=Subquery(
        CommentPost.objects.filter(
            post=OuterRef('pk')
        ).values('content1').order_by('-date_posted')[:1]
    )
)

然后在模板中，您可以使用：

{% for post in posts %}
    {{ post.last_comment }}
{% endfor %}