from django.shortcuts import render
from .models import Category, Good
from django.http import Http404
def index(request, cat_id):
	cats = Category.objects.all().order_by('name')
	if cat_id == None:
		cat = Category.objects.first()
	else:
		cat = Category.objects.get(pk = cat_id)
	goods = Good.objects.filter(category = cat).order_by('name')
	return render(request, 'index.html', {'category':cat,'cats':cats,'goods':goods})
def good(request, good_id,):
	
	try:
		good = Good.objects.get(pk = good_id)
	except Good.DoesNotExist:
		raise Http404
	return render(request,'good.html',{'good':good})

 from django.db import models
class Category(models.Model):
	name = models.CharField(max_length=30, unique=True)
	def __str__(self):
		return self.name
class Good(models.Model):
	name = models.CharField(max_length=50,unique=True)
	description = models.TextField()
	in_stock = models.BooleanField(default=True, db_index=True)
	category = models.ForeignKey(Category,on_delete=models.CASCADE)
	def __str__(self):
		s = self.name
		if not self.in_stock:
			s=s + '( Нет в наличие )'
		return s

 <ul>
			{% for cat in cats %}
				<li>
					<a href="/goods/{{cat.id}}/">{{cat.name}}</a>
				</li>
			{% endfor %}
		</ul>

 <ul>
			
</ul>

 return render(request, 'index.html', {'category':cat,'cats':cats,'goods':goods})