Python-сообщество

class SiteCategory(models.Model):
    freelance_site = models.ForeignKey(FreelanceSite)
    site_category = models.CharField(max_length=70)
    
    def __unicode__(self):
        return self.site_category

class Category(models.Model):
    site_category = models.ManyToManyField(SiteCategory)
    category = models.CharField(max_length=70)
    
    def __unicode__(self):
        return self.category

class UsersCategory(models.Model):
    user = models.ForeignKey(User)
    categories = models.ManyToManyField(Category)
    
    def __unicode__(self):
        return self.user.username

def setcat(request):
    if not request.user.is_authenticated():
        return HttpResponseRedirect('/')
    if request.method == 'POST':
        check_list = []
        while i <= len(category_list):
            checkbox = 'cat%s' % str(i)
            if checkbox in request.POST: check_list.append(True)
            else: check_list.append(False)
            i += 1
         # здесь непонятно
    category_list = Category.objects.all()
    user_categories = []
    try:
        user_category_list = UsersCategory.objects.get(user=request.user)
    except UsersCategory.DoesNotExist:
        for category in category_list:
            user_categories.append({'category':category, 'check': False})
    else:
        for category in category_list:
            for user_category in user_category_list.categories:
                check = False
                if user_category.category == category_list.category:
                    check = True
                user_categories.append({'category':category, 'check': check})
    return render_to_response('web/setcat.html',
                                  {'user_categories': user_categories,
                                  },
                                   context_instance=RequestContext(request)
                                   )

				<div class="line">
					<form action="" method="post">
						{% for category in user_categories %}
						<p><input type="checkbox" value="{{ category.check }}" name="cat{{ forloop.counter }}">{{ category.category|safe }}</p>
						{% endfor %}
						<input type="submit" value="Сохранить">
					</form>
				</div>