Cancelling events: Allow to cancel all dates in a series

src/pretix/control/forms/orders.py

@@ -526,8 +526,8 @@ class EventCancelForm(forms.Form):
     subevent = forms.ModelChoiceField(
         SubEvent.objects.none(),
         label=pgettext_lazy('subevent', 'Date'),
-        required=True,
-        empty_label=None
+        required=False,
+        empty_label=pgettext_lazy('subevent', 'All dates')
     )
     auto_refund = forms.BooleanField(
         label=_('Automatically refund money if possible'),
@@ -655,11 +655,10 @@ class EventCancelForm(forms.Form):
                         'event': self.event.slug,
                         'organizer': self.event.organizer.slug,
                     }),
-                    'data-placeholder': pgettext_lazy('subevent', 'Date')
+                    'data-placeholder': pgettext_lazy('subevent', 'All dates')
                 }
             )
             self.fields['subevent'].widget.choices = self.fields['subevent'].choices
-            self.fields['subevent'].required = True
         else:
             del self.fields['subevent']
         change_decimal_field(self.fields['keep_fee_fixed'], self.event.currency)

src/tests/base/test_cancelevent.py

@@ -373,6 +373,17 @@ class SubEventCancelTests(TestCase):
         self.order.refresh_from_db()
         assert self.order.status == Order.STATUS_CANCELED
 
+    @classscope(attr='o')
+    def test_cancel_all_subevents(self):
+        cancel_event(
+            self.event.pk, subevent=None,
+            auto_refund=True, keep_fee_fixed="0.00", keep_fee_percentage="0.00",
+            send=True, send_subject="Event canceled", send_message="Event canceled :-(",
+            user=None
+        )
+        self.order.refresh_from_db()
+        assert self.order.status == Order.STATUS_CANCELED
+
     @classscope(attr='o')
     def test_cancel_mixed_order(self):
         gc = self.o.issued_gift_cards.create(currency="EUR")