class Product(models.Model):
    parent = models.ForeignKey(Category)
    name = models.CharField('Название', max_length=100)
    price = models.IntegerField('Цена')
    text = models.TextField('Описание товара')

    size = models.ManyToManyField(Size)
    color = models.ManyToManyField(Color)
    vendor = models.ForeignKey(Brand, blank=True)
    shop = models.ForeignKey(Company, blank=True)

class ProductsIndex(indexes.SearchIndex, indexes.Indexable):
    text = indexes.CharField(document=True, use_template=True)
    name = indexes.CharField(model_attr='name')
    description = indexes.CharField(model_attr='text')
    category = indexes.CharField(model_attr='parent__name')
    color = indexes.CharField(model_attr='color__value')
    size = indexes.CharField(model_attr='size__value')
    vendor = indexes.CharField(model_attr='vendor__name')
    price = indexes.IntegerField(model_attr='price')

    def get_model(self):
        return Product

    def index_queryset(self, using=None):
        return self.get_model().objects.filter(active=True)

class BrandIndex(indexes.SearchIndex, indexes.Indexable):
    # .. ?