Wsrtjtyk

I am learining Django trying to create a blog. I have a ListView of Post model on Homepage. I am trying to add new context data (number of comments from separate model Comment for each item from ListView). However I wasn't able to correctly filter number of Comments for each Post by using __in (it just shows same total number of Comments on each Post item of ListView). Could you please help me with how to get a correct filter to show for each ListView Post item how many Comments does it have?

Thanks!

Post Model:

class Post(models.Model):

    class Meta:

        verbose_name = 'запись'

        verbose_name_plural = 'записи'



    title = models.CharField('название', max_length=300, help_text='Не более 300 знаков')

    content = models.TextField('текст записи')

    date_posted = models.DateTimeField('дата публикации', default=timezone.now)

    author = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name='автор')



    def __str__(self):

        return self.title



    def get_absolute_url(self):

        return reverse('post-detail', kwargs={'pk': self.pk})

Comment model:

class Comment(models.Model):

    class Meta:

        verbose_name = 'комментарий'

        verbose_name_plural = 'комментарии'



    content = models.CharField('текст комментария', max_length=500, help_text='Не более 500 знаков')

    date_posted = models.DateTimeField('дата публикации', default=timezone.now)

    author = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name = 'автор')

    postid = models.ForeignKey(Post, on_delete=models.CASCADE)

ListView in views.py:

class PostListView(ListView):

    model = Post

    template_name = 'blog/home.html'

    context_object_name = 'posts'

    ordering = ['-date_posted']

    paginate_by = 5



    def get_context_data(self, **kwargs):

        context = super().get_context_data(**kwargs)

        context['comments'] = Comment.objects.filter(postid__in = self.object_list)

        return context

Context data that I use in html template:

{% for post in posts%}

 {{ post.content }}

 {{ comments.count }}

{% endfor %}

What you probably want is to .annotate(..) the queryset such that each Post object contains an extra attribute with the number of comments:

from django.db.models import Count



class PostListView(ListView):

    model = Post

    queryset = Post.objects.annotate(

        num_comments=Count('comment')

    )

    template_name = 'blog/home.html'

    context_object_name = 'posts'

    ordering = ['-date_posted']

    paginate_by = 5

In the template, you can then fetch the .num_comment attribute (this is only added to Post objects that originate from this queryset), and render it with:

{% for post in posts%}

   {{ post.content }}

   {{ post.num_comments }}

{% endfor %}