Владимир

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)

Product.objects.filter(category__office=current_office)

STOP_LIST = [
    'мат',
    'мат',
    'мат',
]

class ContactForm(forms.Form):
    ...

    def clean_text(self):
        text = self.cleaned_data['text']
        for word in STOP_LIST:
            if word in text:
                raise forms.ValidationError("Вы позволили себе немного лишнего! Одумайтесь и исправьте текст!")
        return text

from django.db.models.signals import post_save
from django.dispatch import receiver

@receiver(post_save, sender=User, created)
def save_profile(sender, instance, **kwargs):
    # instance — это сохранённый экземпляр модели User
    # created — это флаг, указывающий был ли пользователь создан, или сохранён уже существующий

class ServiceCreateView(CreateView):
    model = Service
    template_name = 'elitemservice/main.html'

    def form_valid(self, form):
        resp = super(ServiceCreateView, self).form_valid(form)
        # после вызова суперметода в self.object находится созданный по форме объект
        user = self.request.user
        if user.is_authenticated:
            user.loads_services.create(
                pk=self.object.pk,
                name_service=self.object.name_service,
                about_service=self.object.about_service,
                file_service=self.object.file_service,
            )
            user.save()
        return resp

path('<path:categories>/', viewsCategoryDetailView.as_view(), name='category')

def get(self, request, *args, **kwargs):
    categories = kwargs.get('categories').strip('/')  # 'cat/subcat/sub-subcat'
    categories = categories.split('/') # ['cat', 'subcat', 'sub-subcat']
    ...

news = News.objects.filter(site__domain=request.get_host())

db_name = get_db_name_by_host(request.get_host())
news = News.objects.using(db_name).all()

from django.db.models import F

class Quiz(models.Model):
    ...
    def increase_views(self):
        self.__class__.objects.filter(pk=self.pk).update(views=F('views') + 1)

class News(models.Model):
    title = models.CharField(u'заголовок', max_length=200)
    image = models.ImageField(u'изображение', upload_to='images/%Y/%m/%d/', max_length=250)
    text = models.TextField(u'текст')

urlpatterns = [
    path('quiz/bookmark/create-remove/<slug:slug>/', views.CreateRemoveBookmarkAPI.as_view(),
        name="bookmark-create-remove-api"),
]

@receiver(post_save, sender=FingerPrint)
def update_calculated_fields(sender, instance, **kwargs):
    tlsh = instance.calculate_tlsh()
    sender.objects.filter(pk=instance.pk).update(tlsh=tlsh)