Pagination doesn't fully work for comments. All comments on one page and on other pages it's the same thing.

Using Django Using the ORM
1

Django sees the pagination and the page shows switching to other pages. But when I go to another page, the comments are exactly the same as on other pages. On the home page, the pagination works fully.

In the terminal:
“GET /game_detail/dead-by-daylight/?page=1 HTTP/1.1” 200 28206
“GET /game_detail/dead-by-daylight/?page=3 HTTP/1.1” 200 28209

views.py

    class GameDetail(LoginRequiredMixin, DataMixin, DetailView):
    model = Game
    context_object_name = 'game'
    template_name = 'main/game_detail.html'
 
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        comments = Comment.objects.filter(game=self.object).select_related('author', 'game')
        for comment in comments:
            comment.str_value = comment.text
        paginator = Paginator(comments, self.paginate_by) 
        page_number = self.request.GET.get('page')
        page_obj = paginator.get_page(page_number)
        context['page_obj'] = page_obj
        context['comments'] = comments
        context['game'] = self.object
        context['average_rating'] = self.object.get_average_rating()
        context['form'] = CommentForm
        return context

utils.py

class DataMixin:
    paginate_by = 3

comments_list.html

   {% if page_obj %}
       <div class="pagination">
           <span class="step-links">
               {% if page_obj.has_previous %}
                   <a href="?page=1">&laquo; First</a>
                   <a href="?page={{ page_obj.previous_page_number }}">Previous</a>
               {% endif %}
               <span class="current">
                   Page {{ page_obj.number }} of {{ page_obj.paginator.num_pages }}.
               </span>
               {% if page_obj.has_next %}
                   <a href="?page={{ page_obj.next_page_number }}">Next</a>
                   <a href="?page={{ page_obj.paginator.num_pages }}">Last &raquo;</a>
               {% endif %}
           </span>
       </div>
   {% endif %}
2

Hello there!
You haven’t shown your Comment model, but I’m assuming that you don’t have a default ordering on the Meta class, and it’s not explicitly calling order_by on your queryset.
I found that this behavior of the Paginator to be really misleading, it won’t fail if you pass an unordered queryset, just emit a warning. And passing a unordered queryset results in “inconsistent pages” that looks like the symptom that you’re describing.

3

I have order by. And i use MPTT in Comment model.

My model.

class Comment(MPTTModel):
    game = models.ForeignKey(
        Game, on_delete=models.CASCADE,
        related_name='comments',
    )
    parent = TreeForeignKey(
        'self',
        on_delete=models.CASCADE,
        null=True,
        blank=True,
        related_name='children',
        db_index=True,
    )
    author = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name='comments_author',
        db_index=True
    )
    text = models.TextField()
    time_add = models.DateTimeField(auto_now_add=True)
    status = models.BooleanField(default=True)

    class MPTTMeta:
        ordering_insertion_by = ['status']
4

I don’t see where are you applying an order_by.
Can you please check this by adding this line on your view?

print("HAS ORDER BY ON QUERYSET", comments.ordered)

5

print() gives HAS ORDER BY ON QUERYSET True

Here order by:

ordering_insertion_by = ['status']

Or is it something else?

6

Sorry, i don’t know all details about MPTT model. But this is probably related to displaying comments from different tree levels based on the status?
That’s just a guess though, maybe other people can help you a bit more as i’m not experienced on MPTT

7

Problem solved.

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        comments = Comment.objects.filter(game=self.object).select_related('author', 'game')

        page = self.request.GET.get('page')
        paginator = Paginator(comments, 15)
        try:
            comments = paginator.page(page)
        except PageNotAnInteger:
            comments = paginator.page(1)
        except EmptyPage:
            comments = paginator.page(paginator.num_pages)

        user = self.request.user
        user_rating = None
        if user.is_authenticated:
            user_rating = UserGameRating.objects.filter(profile=user.profile, game=self.object).first()
        context['comments'] = comments
        context['game'] = self.object
        context['user_rating'] = user_rating
        context['average_rating'] = self.object.get_average_rating()
        context['form'] = CommentForm
        return context