pelase see bleow model defination

class Product(models.Model):
        name = models.CharField(max_length=200, blank=True, null=True)
        prduct_type = models.CharField(max_length=30, blank=True, null=True)

class ProductRateInfo(models.Model):
    product= models.ForeignKey(Product, on_delete=models.CASCADE, related_name='rate_info')
    season_start = models.DateField(blank=True, null=True)
    season_end = models.DateField(blank=True, null=True)
    sbr_rate = models.FloatField(default=0)

While feteching the product we need apply sorting ProductRateInfo.sbr_rate column

Tried below method but its not working

product_qs = Product.object.fitler(prduct_type='demotest').prefetch_related('rate_info')

Thanks in advance