Prevent changing ticket secret of gift-card-issuing order positions (#6281)

src/pretix/control/templates/pretixcontrol/order/change.html

@@ -284,6 +284,14 @@
                             </div>
                             <div class="col-sm-4">
                                 {% bootstrap_field position.form.operation_secret layout='inline' %}
+                                {% if position.issued_gift_cards.exists %}
+                                    <div class="alert alert-info">
+                                        {% blocktrans trimmed %}
+                                        Ticket secrets of order positions that have been used to issue a gift card can not
+                                        be changed. Only the link will be changed in this case.
+                                        {% endblocktrans %}
+                                    </div>
+                                {% endif %}
                             </div>
                         </div>
 

src/pretix/control/views/orders.py

@@ -64,7 +64,7 @@ from django.urls import reverse
 from django.utils import formats
 from django.utils.formats import date_format, get_format
 from django.utils.functional import cached_property
-from django.utils.html import conditional_escape, escape
+from django.utils.html import conditional_escape, escape, format_html
 from django.utils.http import url_has_allowed_host_and_scheme
 from django.utils.safestring import mark_safe
 from django.utils.timezone import make_aware, now
@@ -79,7 +79,7 @@ from pretix.base.email import get_email_context
 from pretix.base.exporter import MultiSheetListExporter
 from pretix.base.i18n import language
 from pretix.base.models import (
-    CachedFile, CachedTicket, Checkin, Invoice, InvoiceAddress, Item,
+    CachedFile, CachedTicket, Checkin, GiftCard, Invoice, InvoiceAddress, Item,
     ItemVariation, LogEntry, Order, QuestionAnswer, Quota,
     ScheduledEventExport, generate_secret,
 )
@@ -1994,7 +1994,7 @@ class OrderChange(OrderView):
         positions = list(self.order.positions.select_related(
             'item', 'item__tax_rule', 'used_membership', 'used_membership__membership_type', 'tax_rule',
             'seat', 'subevent',
-        ).prefetch_related('granted_memberships'))
+        ).prefetch_related('granted_memberships', 'issued_gift_cards'))
         for p in positions:
             p.form = OrderPositionChangeForm(prefix='op-{}'.format(p.pk), instance=p, items=self.items,
                                              initial={'seat': p.seat.seat_guid if p.seat else None},
@@ -2261,6 +2261,12 @@ class OrderContactChange(OrderView):
     def get_context_data(self, **kwargs):
         ctx = super().get_context_data()
         ctx['form'] = self.form
+        if self.order.all_positions.filter(Exists(GiftCard.objects.filter(issued_in=OuterRef('pk')))).exists():
+            self.form.fields['regenerate_secrets'].help_text = format_html(
+                '{}<br><br><strong><span class="fa fa-warning"></span> {}</strong>',
+                self.form.fields['regenerate_secrets'].help_text,
+                _("Ticket secrets of order positions that have been used to issue a gift card can not be changed. Only the link will be changed in this case."),
+            )
         return ctx
 
     @cached_property