Do not allow currency codes that to not represent money (#4056)

* Do not allow currency codes that to not represent money

* Rebase migration

* Fix blacklist

src/pretix/base/migrations/0263_auto_20240409_0732.py

@@ -0,0 +1,26 @@
+# Generated by Django 4.2.10 on 2024-04-09 07:32
+
+from django.db import migrations
+
+
+def change_currencies(apps, schema_editor):
+    Event = apps.get_model("pretixbase", "Event")
+    Event.objects.filter(
+        currency__in={
+            'XAG', 'XAU', 'XBA', 'XBB', 'XBC', 'XBD', 'XDR', 'XPD', 'XPT', 'XSU', 'XTS', 'XUA',
+        }
+    ).update(currency='XXX')
+
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pretixbase", "0262_subevent_comment"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            change_currencies, migrations.RunPython.noop
+        )
+    ]

src/pretix/base/models/event.py

@@ -1237,6 +1237,9 @@ class Event(EventMixin, LoggedModel):
         if self.has_paid_things and not self.has_payment_provider:
             issues.append(_('You have configured at least one paid product but have not enabled any payment methods.'))
 
+        if self.has_paid_things and self.currency == "XXX":
+            issues.append(_('You have configured at least one paid product but have not configured a currency.'))
+
         if not self.quotas.exists():
             issues.append(_('You need to configure at least one quota to sell anything.'))
 

src/pretix/base/services/orders.py

@@ -199,6 +199,7 @@ error_messages = {
     ),
     'addon_no_multi': gettext_lazy('You can select every add-on from the category %(cat)s for the product %(base)s at most once.'),
     'addon_already_checked_in': gettext_lazy('You cannot remove the position %(addon)s since it has already been checked in.'),
+    'currency_XXX': gettext_lazy('Paid products not supported without a valid currency.'),
 }
 
 logger = logging.getLogger(__name__)
@@ -1129,6 +1130,9 @@ def _perform_order(event: Event, payment_requests: List[dict], position_ids: Lis
         id__in=position_ids, event=event
     )
 
+    if shown_total is not None and Decimal(shown_total) > Decimal("0.00") and event.currency == "XXX":
+        raise OrderError(error_messages['currency_XXX'])
+
     validate_order.send(
         event,
         payment_provider=payment_requests[0]['provider'] if payment_requests else None,  # only for backwards compatibility
@@ -2125,6 +2129,9 @@ class OrderChangeManager:
                     )
 
     def _check_paid_to_free(self):
+        if self.event.currency == 'XXX' and self.order.total + self._totaldiff > Decimal("0.00"):
+            raise OrderError(error_messages['currency_XXX'])
+
         if self.order.total == 0 and (self._totaldiff < 0 or (self.split_order and self.split_order.total > 0)) and not self.order.require_approval:
             if not self.order.fees.exists() and not self.order.positions.exists():
                 # The order is completely empty now, so we cancel it.