Цикл for, Page not found (404)

class Category(models.Model):
    name = models.CharField(max_length=255, verbose_name='Название категории', default='')
    alias = models.SlugField(verbose_name='Alias категории', default='')
    image = models.ImageField(null=True, blank=True, upload_to='image/', verbose_name='Изображение')
 
    class Meta:
        verbose_name = "Категория"
        verbose_name_plural = "Категории"
 
    def __str__(self):
        return '%s' % self.name

class Items(models.Model):
    name = models.CharField(max_length=15, verbose_name='Название товара', default='')
    price = models.IntegerField(default=0, verbose_name='Цена')
    # image = models.CharField(max_length=255, verbose_name='Картинка', default='')
    image = models.ImageField(null=True, blank=True, upload_to='image/', verbose_name='Изображение')
    alias = models.SlugField(verbose_name='Alias товара', default='')
 
    category = models.ForeignKey(Category, default=None, blank=True, null=True)
 
    class Meta:
        verbose_name = "Товар"
        verbose_name_plural = "Товары"
 
    def __str__(self):
        return 'Товар %s' % self.name

def products(request, alias):
    try:
        product = Items.objects.get(alias=alias)
        title = product.name
    except:
        raise Http404("Объект не найден")
 
    context = {
        'product': product,
        'title': title,
    }
 
    return render(request, 'product/product.html', context)
 
 
def get_category(request, alias):
    try:
        category = Category.objects.get(alias=alias)
        products = Items.objects.filter(category=category)
        title = category.name
    except:
        raise Http404('Объекты не найден')
    context = {
        'products': products,
        'category': category,
        'title': title,
    }
    return render(request, 'popular/popular.html', context)
 
 
def popular(request):
    try:
        title = 'Популярные'
        products = Items.objects.all()
        category = Category.objects.get()
    except:
        raise Http404('Объекты не найден')
    context = {
        'products': products,
        'category': category,
        'title': title,
 
    }
    return render(request, 'popular/popular.html', context)

url(r'^admin/', admin.site.urls),
    url(r'^$', views.popular, name='popular'),
    url(r'^product/(?P<alias>[^/]+)', views.products, name='product'),
    url(r'^category/(?P<alias>[-\w]+)/$', views.get_category, name='get_category'),

{% for category in ? %}

{% for value in category %}
{{value.name}}
{{value.alias}}
{{value.image}}
{% endfor %}

{{category.name}}
{{category.alias}}
{{category.image}}

{% for value in category %}
{{value.name}}
{{value.alias}}
{{value.image}}
{% endfor %}

def products(request, alias):
    product = Items.objects.get(alias=alias)
    title = product.name
 
    context = {
        'product': product,
        'title': title,
    }
 
    return render(request, 'product/product.html', context)
 
 
def get_category(request, alias):
 
    category = Category.objects.filter(alias=alias)
    products = Items.objects.filter(category=category)
    title = category.name()
 
    context = {
        'products': products,
        'category': category,
        'title': title,
    }
    return render(request, 'popular/popular.html', context)
 
 
def popular(request, alias):
    title = 'Популярные'
    products = Items.objects.all()
    category = Category.objects.filter(alias=alias)
 
    context = {
        'products': products,
        'category': category,
        'title': title,
 
    }
    return render(request, 'popular/popular.html', context)