Order change manager: Allow to disable invoice issuing

src/pretix/base/services/orders.py

@@ -904,12 +904,13 @@ class OrderChangeManager:
     SplitOperation = namedtuple('SplitOperation', ('position',))
     RegenerateSecretOperation = namedtuple('RegenerateSecretOperation', ('position',))
 
-    def __init__(self, order: Order, user=None, auth=None, notify=True):
+    def __init__(self, order: Order, user=None, auth=None, notify=True, reissue_invoice=True):
         self.order = order
         self.user = user
         self.auth = auth
         self.event = order.event
         self.split_order = None
+        self.reissue_invoice = reissue_invoice
         self._committed = False
         self._totaldiff = 0
         self._quotadiff = Counter()
@@ -1392,7 +1393,7 @@ class OrderChangeManager:
 
     def _reissue_invoice(self):
         i = self.order.invoices.filter(is_cancellation=False).last()
-        if i and self._invoice_dirty:
+        if self.reissue_invoice and i and self._invoice_dirty:
             generate_cancellation(i)
             generate_invoice(self.order)
 

src/pretix/control/forms/orders.py

@@ -168,6 +168,15 @@ class OtherOperationsForm(forms.Form):
             'Use with care and only if you need to. Note that rounding differences might occur in this procedure.'
         )
     )
+    reissue_invoice = forms.BooleanField(
+        label=_('Issue a new invoice if required'),
+        required=False,
+        initial=True,
+        help_text=_(
+            'If an invoice exists for this order and this operation would change its contents, the old invoice will '
+            'be cancelled and a new invoice will be issued.'
+        )
+    )
     notify = forms.BooleanField(
         label=_('Notify user'),
         required=False,

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

@@ -215,6 +215,7 @@
                         </div>
                     {% endif %}
                     {% bootstrap_field other_form.recalculate_taxes layout="control" %}
+                    {% bootstrap_field other_form.reissue_invoice layout="control" %}
                     {% bootstrap_field other_form.notify layout="control" %}
                 </div>
             </div>

src/pretix/control/views/orders.py

@@ -1297,7 +1297,8 @@ class OrderChange(OrderView):
         ocm = OrderChangeManager(
             self.order,
             user=self.request.user,
-            notify=notify
+            notify=notify,
+            reissue_invoice=self.other_form.cleaned_data['reissue_invoice'] if self.other_form.is_valid() else True
         )
         form_valid = self._process_add(ocm) and self._process_change(ocm) and self._process_other(ocm)
 

src/tests/base/test_orders.py

@@ -1219,6 +1219,15 @@ class OrderChangeManagerTests(TestCase):
         self.ocm.commit()
         assert self.order.invoices.count() == 3
 
+    @classscope(attr='o')
+    def test_reissue_invoice_disabled(self):
+        self.ocm.reissue_invoice = False
+        generate_invoice(self.order)
+        assert self.order.invoices.count() == 1
+        self.ocm.add_position(self.ticket, None, Decimal('0.00'))
+        self.ocm.commit()
+        assert self.order.invoices.count() == 1
+
     @classscope(attr='o')
     def test_dont_reissue_invoice_on_free_product_changes(self):
         self.event.settings.invoice_include_free = False