How to automatically link posts to comments?

Question

Django

In general, there is a small project. Through the forms, it turns out to bind only if you select in the selection window (in the post form) what we leave a comment on, but it is necessary that this be done without user participation.
Model

class Article(models.Model):
    """
    Модель для создания новостей на главной странице
    """
    #переменные модели

    def get_absolute_url(self):
        return reverse('articles_url', kwargs={'slug': self.slug})

class Comment(models.Model):
    post = models.ForeignKey(Article, related_name='post', on_delete=models.CASCADE)
    author = models.ForeignKey(User, on_delete=models.CASCADE, verbose_name=u"Автор", related_name="author")
    body = models.TextField(max_length=1000)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

view

def articles(request, slug):
    articles = get_object_or_404(Article, slug__iexact=slug)
    #Комментарии

    if request.method == 'POST':
        form = CommentForm(request.POST)
        if form.is_valid():
            form.instance.author = request.user
            #form.instance.post = request.article
            #Я думаю, что нужно корректировать строку выше
            form.save()
            return redirect("/")
        else:
            pass
            #messages.error(request, ('Пожалуйста, исправьте ошибки.'))
    else:
        form = CommentForm(instance=request.user)
    comment = Comment.objects.order_by('-pk')
    context = {
        'form':form,
        'comments': comment,
        'articles': articles,
    }
    return render(request, 'home/one_news.html', context)

Here, as I believe, it is necessary to bind somehow through the view, but I don’t understand exactly how.
NOT NULL constraint failed: home_comment.post_id This is the error that comes out if the post variable is not displayed through the form.
And how to show comments only for the article to which they refer? comment = Comment.objects.order_by('-pk') this option shows all comments on each article page.

Answer 1

post = models.ForeignKey(
    Article,
    related_name='post',
    on_delete=models.CASCADE,
    editable=False  # !!!
)

def article(request, slug):
    article = get_object_or_404(Article, slug__iexact=slug)

    # Комментарии
    if request.method == 'POST':
        comment_form = CommentForm(request.POST)
        if comment_form.is_valid():
            comment_form.instance.author = request.user
            comment_form.instance.post = article
            comment_form.save()
            return redirect('/')
    else:
        comment_form = CommentForm()

    comments = Comment.objects.order_by('-pk')
    context = {
        'article':      article,
        'comments':     comments,
        'comment_form': comment_form,
    }
    return render(request, 'home/one_news.html', context)