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
113 lines
3.9 KiB
Python
113 lines
3.9 KiB
Python
import logging
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from datetime import timedelta
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from django.db.models import F, Sum
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from django.db.models.signals import (
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m2m_changed,
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post_delete,
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post_save,
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pre_delete,
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pre_save,
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)
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from django.dispatch import receiver
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from django.utils.timezone import now
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from games.models import Game, GameStatusChange, Purchase, Session
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logger = logging.getLogger("games")
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@receiver(pre_save, sender=Purchase)
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def store_purchase_price_snapshot(sender, instance, **kwargs):
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"""Store old price values before save so we can detect changes."""
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if instance.pk is not None:
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try:
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old_instance = sender.objects.get(pk=instance.pk)
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instance._old_price = old_instance.price
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instance._old_currency = old_instance.price_currency
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except sender.DoesNotExist:
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pass
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@receiver(post_save, sender=Purchase)
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def mark_needs_price_update(sender, instance, created, **kwargs):
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"""Mark purchase for price update if price or currency changed."""
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if not created and hasattr(instance, "_old_price"):
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if (
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instance.price != instance._old_price
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or instance.price_currency != instance._old_currency
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):
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sender.objects.filter(pk=instance.pk).update(needs_price_update=True)
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@receiver(m2m_changed, sender=Purchase.games.through)
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def update_num_purchases(sender, instance, action, reverse, **kwargs):
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if not reverse and action.startswith("post_"):
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instance.num_purchases = instance.games.count()
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instance.updated_at = now()
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instance.save(update_fields=["num_purchases", "updated_at"])
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@receiver(pre_delete, sender=Game)
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def update_purchase_counts_on_game_delete(sender, instance, **kwargs):
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"""
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Update num_purchases on related Purchase objects when a Game is deleted.
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m2m_changed is not fired when a related object is deleted.
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"""
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for purchase in instance.purchases.all():
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if purchase.num_purchases > 0:
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purchase.num_purchases -= 1
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if purchase.num_purchases == 0:
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purchase.delete()
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else:
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purchase.updated_at = now()
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purchase.save(update_fields=["num_purchases", "updated_at"])
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@receiver([post_save, post_delete], sender=Session)
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def update_game_playtime(sender, instance, **kwargs):
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# During cascade deletes the related Game may already have been removed.
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# Use the FK id to look up the Game safely and bail out if it no longer exists.
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game_pk = getattr(instance, "game_id", None)
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if not game_pk:
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return
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game = Game.objects.filter(pk=game_pk).first()
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if not game:
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return
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total_playtime = game.sessions.aggregate(
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total_playtime=Sum(F("duration_calculated") + F("duration_manual"))
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)["total_playtime"]
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game.playtime = total_playtime if total_playtime else timedelta(0)
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game.save(update_fields=["playtime"])
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@receiver(pre_save, sender=Game)
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def game_status_changed(sender, instance, **kwargs):
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"""
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Signal handler to create a GameStatusChange record whenever a Game's status is updated.
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"""
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try:
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old_instance = sender.objects.get(pk=instance.pk)
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old_status = old_instance.status
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logger.info("[game_status_changed]: Previous status exists.")
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except sender.DoesNotExist:
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# Handle the case where the instance was deleted before the signal was sent
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logger.info("[game_status_changed]: Previous status does not exist.")
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return
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if old_status != instance.status:
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logger.info(
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"[game_status_changed]: Status changed from {} to {}".format(
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old_status, instance.status
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)
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)
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GameStatusChange.objects.create(
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game=instance,
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old_status=old_status,
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new_status=instance.status,
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timestamp=now(),
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)
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else:
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logger.info("[game_status_changed]: Status has not changed")
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