Allow to exclude free products from invoices

src/pretix/base/services/invoices.py

@@ -3,6 +3,7 @@ from decimal import Decimal
 
 from django.core.files.base import ContentFile
 from django.db import transaction
+from django.db.models import Count
 from django.utils import timezone
 from django.utils.translation import pgettext, ugettext as _
 from i18nfield.strings import LazyI18nString
@@ -47,9 +48,16 @@ def build_invoice(invoice: Invoice) -> Invoice:
         invoice.save()
         invoice.lines.all().delete()
 
-        positions = list(invoice.order.positions.select_related('addon_to', 'item', 'variation'))
+        positions = list(
+            invoice.order.positions.select_related('addon_to', 'item', 'variation').annotate(
+                addon_c=Count('addons')
+            )
+        )
         positions.sort(key=lambda p: p.sort_key)
         for p in positions:
+            if not invoice.event.settings.invoice_include_free and p.price == Decimal('0.00') and not p.addon_c:
+                continue
+
             desc = str(p.item.name)
             if p.variation:
                 desc += " - " + str(p.variation.value)

src/pretix/base/services/orders.py

@@ -545,6 +545,7 @@ class OrderChangeManager:
         self._totaldiff = 0
         self._quotadiff = Counter()
         self._operations = []
+        self._invoice_dirty = False
 
     def change_item(self, position: OrderPosition, item: Item, variation: Optional[ItemVariation]):
         if (not variation and item.has_variations) or (variation and variation.item_id != item.pk):
@@ -560,6 +561,9 @@ class OrderChangeManager:
         if not new_quotas:
             raise OrderError(self.error_messages['quota_missing'])
 
+        if self.order.event.settings.invoice_include_free or price != Decimal('0.00') or position.price != Decimal('0.00'):
+            self._invoice_dirty = True
+
         self._totaldiff = price - position.price
         self._quotadiff.update(new_quotas)
         self._quotadiff.subtract(position.quotas)
@@ -576,6 +580,9 @@ class OrderChangeManager:
         if not new_quotas:
             raise OrderError(self.error_messages['quota_missing'])
 
+        if self.order.event.settings.invoice_include_free or price != Decimal('0.00') or position.price != Decimal('0.00'):
+            self._invoice_dirty = True
+
         self._totaldiff = price - position.price
         self._quotadiff.update(new_quotas)
         self._quotadiff.subtract(position.quotas)
@@ -583,6 +590,10 @@ class OrderChangeManager:
 
     def change_price(self, position: OrderPosition, price: Decimal):
         self._totaldiff = price - position.price
+
+        if self.order.event.settings.invoice_include_free or price != Decimal('0.00') or position.price != Decimal('0.00'):
+            self._invoice_dirty = True
+
         self._operations.append(self.PriceOperation(position, price))
 
     def cancel(self, position: OrderPosition):
@@ -590,6 +601,9 @@ class OrderChangeManager:
         self._quotadiff.subtract(position.quotas)
         self._operations.append(self.CancelOperation(position))
 
+        if self.order.event.settings.invoice_include_free or position.price != Decimal('0.00'):
+            self._invoice_dirty = True
+
     def add_position(self, item: Item, variation: ItemVariation, price: Decimal, addon_to: Order = None,
                      subevent: SubEvent = None):
         if price is None:
@@ -609,6 +623,9 @@ class OrderChangeManager:
         if not new_quotas:
             raise OrderError(self.error_messages['quota_missing'])
 
+        if self.order.event.settings.invoice_include_free or price != Decimal('0.00'):
+            self._invoice_dirty = True
+
         self._totaldiff = price
         self._quotadiff.update(new_quotas)
         self._operations.append(self.AddOperation(item, variation, price, addon_to, subevent))
@@ -730,7 +747,7 @@ class OrderChangeManager:
 
     def _reissue_invoice(self):
         i = self.order.invoices.filter(is_cancellation=False).last()
-        if i:
+        if i and self._invoice_dirty:
             generate_cancellation(i)
             generate_invoice(self.order)