views.py

from django.db.models import Count
from django.contrib.auth.decorators import login_required
from django.shortcuts import get_object_or_404, redirect, render

from .forms import NewTopicForm, PostForm
from .models import Board, Post, Topic


def home(request):
    boards = Board.objects.all()
    return render(request, 'home.html', {'boards': boards})


def board_topics(request, pk):
    board = get_object_or_404(Board, pk=pk)
    topics = board.topics.order_by('-last_updated').annotate(replies=Count('posts') - 1)
    return render(request, 'topics.html', {'board': board, 'topics': topics})


@login_required
def new_topic(request, pk):
    board = get_object_or_404(Board, pk=pk)
    if request.method == 'POST':
        form = NewTopicForm(request.POST)
        if form.is_valid():
            topic = form.save(commit=False)
            topic.board = board
            topic.starter = request.user
            topic.save()
            Post.objects.create(
                message=form.cleaned_data.get('message'),
                topic=topic,
                created_by=request.user
            )
            return redirect('topic_posts', pk=pk, topic_pk=topic.pk)
    else:
        form = NewTopicForm()
    return render(request, 'new_topic.html', {'board': board, 'form': form})


def topic_posts(request, pk, topic_pk):
    topic = get_object_or_404(Topic, board__pk=pk, pk=topic_pk)
    return render(request, 'topic_posts.html', {'topic': topic})


@login_required
def reply_topic(request, pk, topic_pk):
    topic = get_object_or_404(Topic, board__pk=pk, pk=topic_pk)
    if request.method == 'POST':
        form = PostForm(request.POST)
        if form.is_valid():
            post = form.save(commit=False)
            post.topic = topic
            post.created_by = request.user
            post.save()
            return redirect('topic_posts', pk=pk, topic_pk=topic_pk)
    else:
        form = PostForm()
    return render(request, 'reply_topic.html', {'topic': topic, 'form': form})

Hi, @vitorfs
Calculation works wrong.
I think, need to use without -1
topics = board.topics.order_by('-last_updated').annotate(replies=Count('posts') - 1 )

Same here,
Calculation works wrong.
Removing -1 worked for me.

I removed -1 ,
but it still works wrong without any data in replies line.
anyone have ideas?

I removed -1 , but it still works wrong without any data in replies line. anyone have ideas?

{% for topic in topics %}
you should check topics.html above line.

boards/views.py
def board_topics(request, pk):
board = get_object_or_404(Board, pk=pk)
topics = board.topics.order_by('last_updated').annotate( replies=Count('posts') -1 )
return render(request, 'topics.html', {'board': board, 'topics': topics})