Item.py

class Item(models.Model):
    name = models.CharField(max_length=255)
    
    def get_options(self):
        topics = {}
        for item_option in ItemOption.objects.select_related().all():
            option = item_option.option
            topic = option.topic

            if topic not in topics:
                topics[topic] = []

            topics[topic].append(
                {'title': option.title,
                 'value': item_option.value if item_option.item == self else None})

        return [{'name': topic.name,
                 'options': options} for (topic, options) in topics.items()]

    def get_options_prefetch(self):
        topics = []
        for topic in Topic.objects.prefetch_related(
            'option_set', 'option_set__itemoption_set', 'option_set__itemoption_set__item').all():
            options = []
            for option in topic.option_set.all():
                try:
                    item_option = option.itemoption_set.all()[0]
                    if item_option.item == self:
                        options.append({'title': option.title, 'value': item_option.value})
                    else:
                        options.append({'title': option.title, 'value': None})
                except (ItemOption.DoesNotExist, IndexError):
                    options.append({'title': option.title, 'value': None})
            topics.append({'name': topic.name, 'options': options})
        return topics