注释查询，pk

Question

pk和annotate一起使用应该如何查询？

当客人点击链接时，我需要重定向到用户个人资料。

型号

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)

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 Profil(models.Model):
   first_name = models.CharField(max_length=50)
   last_name = models.CharField(max_length=50)
   age = models.PositiveIntegerField(blank=True, null=True)
   country = models.CharField(max_length=50)
   user = models.OneToOneField(Account, on_delete=models.CASCADE)
   avatar = models.ImageField(default="avatar.png", upload_to="images",validators=[FileExtensionValidator(['png', 'jpg', 'jpeg'])])
   slug = models.SlugField(blank=True)
   gender = models.CharField(max_length=6, choices=GENDER)
   friends = models.ManyToManyField(Account, blank=True, related_name="Friends")
   social_facebook = models.CharField(max_length=250, null=True, blank=True)
   social_instagram = models.CharField(max_length=250, null=True, blank=True)
   social_twitter = models.CharField(max_length=250, null=True, blank=True)
   social_youtube = models.CharField(max_length=250, null=True, blank=True)
   social_linkedin = models.CharField(max_length=250, null=True, blank=True)
   updated = models.DateTimeField(auto_now=True)
   created = models.DateTimeField(auto_now_add=True)

观看次数

   if tag == None:
    my_tag = Posty.objects.annotate(
        latest_comment = Subquery(CommentPost.objects.filter(post=OuterRef('id')).values('content1').order_by('-date_posted')[:1]),
        my_author=Subquery(CommentPost.objects.filter(post=OuterRef('id')).values('user__user__username').order_by('-date_posted')[:1]),
    )

我的用户名正确，但我无法获得正确的重定向：

Answer 1

不幸的是，您需要使用查询集注释CommentPost 的id 信息，就像添加username 信息一样。最终会在原始查询集中添加大量子查询。相反，我建议使用prefetch related 将CommentPost 信息与原始查询集一起预加载（用于减少数据库命中）并直接从模板访问该信息。例如：

# view
my_tag = Posty.objects.prefetch_related('commentpost_set')

# template
{% for post in my_tag %}
    <span><a href="{% url 'home:detail_post' post.pk %}"> {{post.commentpost_set.last.content1}}</a><span>
    <span><a href="{% url 'home:detail_post' post.commentpost_set.last.user.pk %}"> {{post.commentpost_set.last.user.username}}</a><span>
{% endfor %}

另外，last 是一个查询集函数，它返回给定查询集的最后一个对象。我可以通过reverse querying 从Posty 对象访问CommentPost 查询集。