Filter `calculated field` in Django

In SQL filter your fields that fit to your formula is piece of cake since you were taught to use WHERE clause at the first hour of your database101. However, I don’t want to go back date to early day since I have ORM in my hand. Here is my problem

from django.contrib.postgres.fields import DecimalRangeField
from django.db import models


class Premium(models.Model):
    percentage = models.DecimalField(max_digits=10, decimal_places=2)
    sum_insured = DecimalRangeField()   # Insurer accepts this range

    def __str__(self):
        return f"{self.percentage} | {self.sum_insured}"

Please ignore sum_insured range field for now. I am about to show you filter
According to premium it has formula as follows

premium = percentage * given_sum_insured

Therefore I have to make premium column first. Using annotate

query = Premium.objects.annotate(premium=F('percentage') / 100.0 * given_sum_insured)

At this point I can use ORM operator like this is a real field

filtered_qs = query.filter(premium__gte=125)

In my repository it has following topics including filter on calculated field
1. Django REST Framework
2. graphene-django
3. django_filters
4. TestCase of them

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