{% block breadcrumbs %}
    <div class="breadcrumb"><a href="/">Главная</a></div>
{% endblock %}{% extends 'base.html' %}
{% block breadcrumbs %}
    {{ block.super }}
    <div class="breadcrumb"><a href="{% url 'articles:articles' %}">Каталог статей</a></div>
{% endblock %}{% extends 'articles.html' %}
{% block breadcrumbs %}
    {{ block.super }}
    <div class="breadcrumb"><a href="{% url 'articles:article_view' article_id=article.id %}">{{ article.title }}</a></div>
{% endblock %}      
  
  class Category(models.Model):
    parent = models.ForeignKey('self', null=True)
    title = models.CharField(...)
class Product(models.Model):
    title = models.CharField(...)parent = models.ManyToManyField('self', null=True)# in class Category
is_best = models.Boolean(default=False)