Fix #141 -- Caching improvements for ticket outputs

src/pretix/base/models/orders.py

@@ -8,6 +8,8 @@ import pytz
 from django.conf import settings
 from django.db import models
 from django.db.models import F
+from django.db.models.signals import post_delete
+from django.dispatch import receiver
 from django.utils.crypto import get_random_string
 from django.utils.timezone import make_aware, now
 from django.utils.translation import ugettext_lazy as _
@@ -563,3 +565,9 @@ class CachedTicket(models.Model):
     order_position = models.ForeignKey(OrderPosition, on_delete=models.CASCADE)
     cachedfile = models.ForeignKey(CachedFile, on_delete=models.CASCADE, null=True)
     provider = models.CharField(max_length=255)
+
+
+@receiver(post_delete, sender=CachedTicket)
+def cached_file_delete(sender, instance, **kwargs):
+    if instance.cachedfile:
+        instance.cachedfile.delete()

src/pretix/base/services/orders.py

@@ -21,7 +21,7 @@ from pretix.base.models import (
     CartPosition, Event, Item, ItemVariation, Order, OrderPosition, Quota,
     User, Voucher,
 )
-from pretix.base.models.orders import InvoiceAddress
+from pretix.base.models.orders import CachedTicket, InvoiceAddress
 from pretix.base.payment import BasePaymentProvider
 from pretix.base.services.async import ProfiledTask
 from pretix.base.services.invoices import (
@@ -579,9 +579,13 @@ class OrderChangeManager:
                 self._perform_operations()
             self._recalculate_total_and_payment_fee()
             self._reissue_invoice()
+            self._clear_tickets_cache()
         self._check_paid_to_free()
         self._notify_user()
 
+    def _clear_tickets_cache(self):
+        CachedTicket.objects.filter(order_position__order=self.order).delete()
+
     def _get_payment_provider(self):
         responses = register_payment_providers.send(self.order.event)
         pprov = None