QuerySet Helpers

# This will NOT work - price_target is not a database field
Property.objects.filter(price_target__gte=10000)  # FieldError!

from django_cfg.apps.tools.currency.services import annotate_converted_price
 
# Annotate with converted price
qs = annotate_converted_price(
    Property.objects.all(),
    price_field="price",
    currency_field="price_currency",
    target_currency="USD",
    annotation_name="price_usd",
)
 
# Now you can filter/sort by price_usd
qs.filter(price_usd__gte=10000)  # Works!

SELECT *,
  CASE
    WHEN price_currency = 'IDR' THEN price * 0.0000625
    WHEN price_currency = 'THB' THEN price * 0.028
    WHEN price_currency = 'USD' THEN price * 1.0
    ELSE price
  END AS price_usd
FROM properties
WHERE price_usd >= 10000 AND price_usd <= 50000

from django_cfg.apps.tools.currency.services import annotate_converted_price
 
qs = annotate_converted_price(
    queryset=Property.objects.all(),
    price_field="price",
    currency_field="price_currency",
    target_currency="USD",
    annotation_name="price_usd",
)
 
# Filter by converted price
expensive = qs.filter(price_usd__gte=100000)
 
# Order by converted price
sorted_qs = qs.order_by("price_usd")
 
# Access on instances
for prop in qs[:5]:
    print(f"{prop.price} {prop.price_currency} = {prop.price_usd:.2f} USD")

from django_cfg.apps.tools.currency.services import filter_by_converted_price
 
# Filter properties between $100k and $500k USD
qs = filter_by_converted_price(
    queryset=Property.objects.all(),
    price_field="price",
    currency_field="price_currency",
    target_currency="USD",
    min_price=100_000,
    max_price=500_000,
)

from django_cfg.apps.tools.currency.services import get_conversion_rates
 
rates = get_conversion_rates(["IDR", "THB", "KRW"], "USD")
# {'IDR': Decimal('0.0000625'), 'THB': Decimal('0.028'), 'KRW': Decimal('0.00071')}

import django_filters
from django_cfg.apps.tools.currency.services import annotate_converted_price
 
PRICE_TARGET_CURRENCY = "USD"
 
class PropertyFilter(django_filters.FilterSet):
    min_price = django_filters.NumberFilter(method='filter_min_price')
    max_price = django_filters.NumberFilter(method='filter_max_price')
 
    class Meta:
        model = Property
        fields = []
 
    def filter_min_price(self, queryset, name, value):
        """Filter by min price in USD."""
        queryset = annotate_converted_price(
            queryset,
            price_field="price",
            currency_field="price_currency",
            target_currency=PRICE_TARGET_CURRENCY,
            annotation_name="price_usd",
        )
        return queryset.filter(price_usd__gte=value)
 
    def filter_max_price(self, queryset, name, value):
        """Filter by max price in USD."""
        queryset = annotate_converted_price(
            queryset,
            price_field="price",
            currency_field="price_currency",
            target_currency=PRICE_TARGET_CURRENCY,
            annotation_name="price_usd",
        )
        return queryset.filter(price_usd__lte=value)

# Convert to EUR
qs_eur = annotate_converted_price(
    Property.objects.all(),
    price_field="price",
    currency_field="price_currency",
    target_currency="EUR",
    annotation_name="price_eur",
)
 
# Convert to THB
qs_thb = annotate_converted_price(
    Property.objects.all(),
    price_field="price",
    currency_field="price_currency",
    target_currency="THB",
    annotation_name="price_thb",
)