Vouchers: Fix label on redemption page

src/pretix/base/models/vouchers.py

@@ -581,6 +581,10 @@ class Voucher(LoggedModel):
         else:
             return bool(subevent.seating_plan) if subevent else self.event.seating_plan
 
+    @property
+    def min_usages_remaining(self):
+        return max(1, self.min_usages - self.redeemed)
+
     @classmethod
     def annotate_budget_used_orders(cls, qs):
         opq = OrderPosition.objects.filter(

src/pretix/base/services/cart.py

@@ -530,11 +530,11 @@ class CartManager:
             ops.append((listed_price - price_after_voucher, self.VoucherOperation(p, voucher, price_after_voucher)))
 
         for voucher, cnt in list(voucher_use_diff.items()):
-            if 0 < cnt < (voucher.min_usages - voucher.redeemed):
+            if 0 < cnt < voucher.min_usages_remaining:
                 raise CartError(
                     _(error_messages['voucher_min_usages']) % {
                         'voucher': voucher.code,
-                        'number': (voucher.min_usages - voucher.redeemed),
+                        'number': voucher.min_usages_remaining,
                     }
                 )
 
@@ -943,7 +943,7 @@ class CartManager:
         for voucher, count in vouchers.items():
             if not voucher or count == 0:
                 continue
-            if count < (voucher.min_usages - voucher.redeemed):
+            if count < voucher.min_usages_remaining:
                 self._operations = [o for o in self._operations if not (
                     isinstance(o, self.AddOperation) and o.voucher.pk == voucher.pk
                 )]
@@ -953,13 +953,13 @@ class CartManager:
                         self._operations.append(self.RemoveOperation(position=p))
                         err = _(error_messages['voucher_min_usages_removed']) % {
                             'voucher': voucher.code,
-                            'number': (voucher.min_usages - voucher.redeemed),
+                            'number': voucher.min_usages_remaining,
                         }
                 if not err:
                     raise CartError(
                         _(error_messages['voucher_min_usages']) % {
                             'voucher': voucher.code,
-                            'number': (voucher.min_usages - voucher.redeemed),
+                            'number': voucher.min_usages_remaining,
                         }
                     )
         return err

src/pretix/base/services/orders.py

@@ -722,10 +722,10 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
             delete(cp)
 
     for voucher, cnt in v_usages.items():
-        if 0 < cnt < voucher.min_usages - voucher.redeemed:
+        if 0 < cnt < voucher.min_usages_remaining:
             raise OrderError(error_messages['voucher_min_usages'], {
                 'voucher': voucher.code,
-                'number': (voucher.min_usages - voucher.redeemed),
+                'number': voucher.min_usages_remaining,
             })
 
     # Check prices

src/pretix/presale/templates/pretixpresale/event/voucher.html

@@ -411,10 +411,10 @@
             {% if event.presale_is_running and options > 0 %}
                 <div class="row checkout-button-row">
                     <div class="col-md-4 col-md-offset-8 col-xs-12 text-center">
-                        {% if voucher.min_usages > 1 %}
+                        {% if voucher.min_usages_remaining > 1 %}
                             <p class="text-muted">
                                 <small>
-                                    {% blocktrans trimmed with number=voucher.min_usages %}
+                                    {% blocktrans trimmed with number=voucher.min_usages_remaining %}
                                         You need to select at least {{ number }} products.
                                     {% endblocktrans %}
                                 </small>