lukas
e3b53cd4a9
Replace fragile price change detection in Purchase.save() with a lazy dirty flag approach. A pre_save/post_save signal pair detects price/currency changes without extra DB queries, and convert_prices() uses the flag to determine which purchases need conversion. - Add needs_price_update BooleanField with db_index - Add pre_save signal to store old price/currency values - Add post_save signal to set needs_price_update=True when price/currency changes - Simplify Purchase.save() to remove DB reload + comparison logic - Remove price_or_currency_differ_from() method - Update convert_prices() to filter on needs_price_update flag - Extract _get_exchange_rate() and _save_converted_price() helpers - Add tests for the new behavior
101 lines
3.6 KiB
Python
101 lines
3.6 KiB
Python
import logging
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import requests
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from django.db import models
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from django.template.defaultfilters import floatformat
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logger = logging.getLogger("games")
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from games.models import ExchangeRate, Purchase
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# fixme: save preferred currency in user model
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currency_to = "CZK"
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currency_to = currency_to.upper()
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def _get_exchange_rate(currency_from, currency_to, year):
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logger.info(
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f"[convert_prices]: Looking for exchange rate in database: {currency_from}->{currency_to}"
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)
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exchange_rate = ExchangeRate.objects.filter(
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currency_from=currency_from, currency_to=currency_to, year=year
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).first()
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if not exchange_rate:
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logger.info(
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f"[convert_prices]: Getting exchange rate from {currency_from} to {currency_to} for {year}..."
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)
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try:
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response = requests.get(
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f"https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@{year}-01-01/v1/currencies/{currency_from.lower()}.json"
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)
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response.raise_for_status()
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data = response.json()
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currency_from_data = data.get(currency_from.lower())
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rate = currency_from_data.get(currency_to.lower())
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if rate:
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logger.info(f"[convert_prices]: Got {rate}, saving...")
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exchange_rate = ExchangeRate.objects.create(
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currency_from=currency_from,
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currency_to=currency_to,
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year=year,
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rate=floatformat(rate, 2),
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)
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exchange_rate = exchange_rate.rate
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else:
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logger.info("[convert_prices]: Could not get an exchange rate.")
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except requests.RequestException as e:
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logger.info(
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f"[convert_prices]: Failed to fetch exchange rate for {currency_from}->{currency_to} in {year}: {e}"
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)
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elif exchange_rate:
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exchange_rate = exchange_rate.rate
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return exchange_rate
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def _save_converted_price(purchase, converted_price, needs_update):
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logger.info(
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f"Setting converted price of {purchase} to {converted_price} {currency_to} (originally {purchase.price} {purchase.price_currency})"
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)
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purchase.converted_price = converted_price
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purchase.converted_currency = currency_to
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if needs_update:
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purchase.needs_price_update = False
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purchase.save(update_fields=["converted_price", "converted_currency", "needs_price_update"])
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def convert_prices():
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purchases = Purchase.objects.filter(
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models.Q(needs_price_update=True) | models.Q(converted_price__isnull=True)
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).distinct()
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if purchases.count() == 0:
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logger.info("[convert_prices]: No prices to convert.")
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return
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for purchase in purchases:
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needs_update = purchase.needs_price_update
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if purchase.price_currency.upper() == currency_to or purchase.price == 0:
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_save_converted_price(purchase, purchase.price, needs_update)
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continue
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year = purchase.date_purchased.year
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currency_from = purchase.price_currency.upper()
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exchange_rate = _get_exchange_rate(currency_from, currency_to, year)
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if exchange_rate:
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_save_converted_price(
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purchase,
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floatformat(purchase.price * exchange_rate, 0),
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needs_update,
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)
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def calculate_price_per_game():
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"""
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This task is deprecated because price_per_game is now a GeneratedField.
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It is kept here to prevent errors from lingering scheduled tasks.
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"""
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try:
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from django_q.models import Schedule
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Schedule.objects.filter(func="games.tasks.calculate_price_per_game").delete()
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except Exception:
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pass
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