Refs #145 -- Multi-use vouchers

src/pretix/base/models/items.py

@@ -4,8 +4,9 @@ from datetime import datetime
 from decimal import Decimal
 from typing import Tuple
 
+from django.conf import settings
 from django.db import models
-from django.db.models import Q
+from django.db.models import F, Func, Q, Sum
 from django.utils.functional import cached_property
 from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
@@ -577,12 +578,18 @@ class Quota(LoggedModel):
         from pretix.base.models import Voucher
 
         now_dt = now_dt or now()
+        if 'sqlite3' in settings.DATABASES['default']['ENGINE']:
+            func = 'MAX'
+        else:
+            func = 'GREATEST'
+
         return Voucher.objects.filter(
             Q(block_quota=True) &
-            Q(redeemed=False) &
             Q(Q(valid_until__isnull=True) | Q(valid_until__gte=now_dt)) &
             Q(Q(self._position_lookup) | Q(quota=self))
-        ).values('id').distinct().count()
+        ).values('id').aggregate(
+            free=Sum(Func(F('max_usages') - F('redeemed'), 0, function=func))
+        )['free'] or 0
 
     def count_in_cart(self, now_dt: datetime=None) -> int:
         from pretix.base.models import CartPosition
@@ -617,9 +624,9 @@ class Quota(LoggedModel):
         return (
             (  # Orders for items which do not have any variations
                Q(variation__isnull=True) &
-               Q(item__quotas__in=[self])
+               Q(item__quotas=self)
             ) | (  # Orders for items which do have any variations
-                   Q(variation__quotas__in=[self])
+                   Q(variation__quotas=self)
             )
         )
 

src/pretix/base/models/orders.py

@@ -7,6 +7,7 @@ from typing import List, Union
 import pytz
 from django.conf import settings
 from django.db import models
+from django.db.models import F
 from django.utils.crypto import get_random_string
 from django.utils.timezone import make_aware, now
 from django.utils.translation import ugettext_lazy as _
@@ -459,6 +460,8 @@ class OrderPosition(AbstractPosition):
 
     @classmethod
     def transform_cart_positions(cls, cp: List, order) -> list:
+        from . import Voucher
+
         ops = []
         for cartpos in cp:
             op = OrderPosition(order=order)
@@ -471,8 +474,7 @@ class OrderPosition(AbstractPosition):
                 answ.cartposition = None
                 answ.save()
             if cartpos.voucher:
-                cartpos.voucher.redeemed = True
-                cartpos.voucher.save()
+                Voucher.objects.filter(pk=cartpos.voucher.pk).update(redeemed=F('redeemed') + 1)
             cartpos.delete()
         return ops
 

src/pretix/base/models/vouchers.py

@@ -30,7 +30,9 @@ class Voucher(LoggedModel):
     :type event: Event
     :param code: The secret voucher code
     :type code: str
-    :param redeemed: Whether or not this voucher has already been redeemed
+    :param max_usages: The number of times this voucher can be redeemed
+    :type max_usages: int
+    :param redeemed: The number of times this voucher already has been redeemed
     :type redeemed: bool
     :param valid_until: The expiration date of this voucher (optional)
     :type valid_until: datetime
@@ -68,10 +70,14 @@ class Voucher(LoggedModel):
         max_length=255, default=generate_code,
         db_index=True,
     )
-    redeemed = models.BooleanField(
+    max_usages = models.PositiveIntegerField(
+        verbose_name=_("Maximum usages"),
+        help_text=_("Number of times this voucher can be redeemed."),
+        default=1
+    )
+    redeemed = models.PositiveIntegerField(
         verbose_name=_("Redeemed"),
-        default=False,
-        db_index=True
+        default=0
     )
     valid_until = models.DateTimeField(
         blank=True, null=True, db_index=True,
@@ -197,7 +203,7 @@ class Voucher(LoggedModel):
         Returns True if a voucher has not yet been redeemed, but is still
         within its validity (if valid_until is set).
         """
-        if self.redeemed:
+        if self.redeemed >= self.max_usages:
             return False
         if self.valid_until and self.valid_until < now():
             return False