Django order_by price field with linked currency field

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I have real estate model. There are two fields price and currency. People can enter real estate's price in two currency only. However as price field is just numbers and prices are linked to currency, I can not order prices with different currency. Only ordering with the same currency is possible.

Only two currency options are available:

UZS = 'UZS'
USD = 'USD'

CURRENCY_TYPES = (
    (UZS, 'sum'),
    (USD, 'y.e.')
)

class Property(BaseModel):
    price = models.PositiveIntegerField()
    currency = models.CharField(max_length=255, choices=CURRENCY_TYPES)

I tried to change prices to the same currency but then I don't know how to order them.

Property.objects.filter(currency='UZS').annotate(divided_price=F('price') / 10000).values('divided_price')

So rate is

1 USD = 10 000 UZS

10 000 UZS = 1 USD

How to order prices with different currencies?

django python
1 Answers

Use case expression for converting the prices to a common currency value. For example

from django.db.models import Case, When

#...
conversion_rate = 1 / 10_000 # This value can be from an exchange board

qs = Property.objects.annotate(
    price_usd=Case(
        When(currency=UZS, then=F('price') * conversion_rate ),
        # Assumes that the only other currency is USD
        default=F('price')
    )
).order_by('price_usd')
user_51898110
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