models.py

# -*- coding: utf-8 -*-

from __future__ import unicode_literals
from django.db import models

# Create your models here.

class Category(models.Model):
    name = models.CharField('Группа товара', max_length=64)

    def __unicode__(self):
        return self.name


class Product(models.Model):
    category = models.ForeignKey(Category, verbose_name='Группа')
    name = models.CharField('Название товара', max_length=128)
    price = models.DecimalField('Стоимость единицы, руб.', max_digits=10, decimal_places=2)

    def __unicode__(self):
        return self.name + " (" + str(self.price) + ")"

views.py

# -*- coding: utf-8 -*-

from django.shortcuts import render
from django.http import HttpResponse
from django.db.models import Count

from project.main.models import *

# Create your views here.

def home(request):

    products = Product.objects.filter(price__gte=100).values()
    categories = Category.objects.values('id', 'name')\
        .annotate(count=Count('product__id'))\
        .filter(count__gt=10) # where more than 10 products

    categoryProducts = {}

    for product in products:
        catId = product['category_id']

        if not catId in categoryProducts:
            categoryProducts[catId] = []

        categoryProducts[catId].append(product)

    tree = []

    for category in categories:
        catItem = {
            'category_id': category['id'],
            'name': category['name'],
            'productsCount': category['count'],
            'products': categoryProducts[category['id']],
        }

        tree.append(catItem)

    return HttpResponse(tree)