Order change manager: Recalculate tax of zero-valued positions (Z#23223874)

src/pretix/base/datasync/datasync.py

@@ -216,10 +216,7 @@ class OutboundSyncProvider:
 
             try:
                 mapped_objects = self.sync_order(sq.order)
-                actions_taken = [res and res.sync_info.get("action", "") for res_list in mapped_objects.values() for res in res_list]
-                should_write_logentry = any(action not in (None, "nothing_to_do") for action in actions_taken)
-                logger.info('Synced order %s to %s, actions: %r, log: %r', sq.order.code, sq.sync_provider, actions_taken, should_write_logentry)
-                if should_write_logentry:
+                if not all(all(not res or res.sync_info.get("action", "") == "nothing_to_do" for res in res_list) for res_list in mapped_objects.values()):
                     sq.order.log_action("pretix.event.order.data_sync.success", {
                         "provider": self.identifier,
                         "objects": {
@@ -240,7 +237,7 @@ class OutboundSyncProvider:
                     sq.set_sync_error("exceeded", e.messages, e.full_message)
                 else:
                     logger.info(
-                        f"Could not sync order {sq.order.code} to {sq.sync_provider} "
+                        f"Could not sync order {sq.order.code} to {type(self).__name__} "
                         f"(transient error, attempt #{sq.failed_attempts}, next {sq.not_before})",
                         exc_info=True,
                     )

src/pretix/base/models/datasync.py

@@ -86,7 +86,7 @@ class OrderSyncQueue(models.Model):
 
     def set_sync_error(self, failure_mode, messages, full_message):
         logger.exception(
-            f"Could not sync order {self.order.code} to {self.sync_provider} ({failure_mode})"
+            f"Could not sync order {self.order.code} to {type(self).__name__} ({failure_mode})"
         )
         self.order.log_action(f"pretix.event.order.data_sync.failed.{failure_mode}", {
             "provider": self.sync_provider,

src/pretix/base/services/orders.py

@@ -1799,8 +1799,6 @@ class OrderChangeManager:
             tax_rule = tax_rules.get(pos.pk, pos.tax_rule)
             if not tax_rule:
                 continue
-            if not pos.price:
-                continue
 
             try:
                 new_rate = tax_rule.tax_rate_for(ia)
@@ -1817,7 +1815,9 @@ class OrderChangeManager:
                                            override_tax_rate=new_rate, override_tax_code=new_code)
                 self._totaldiff_guesstimate += new_tax.gross - pos.price
                 self._operations.append(self.PriceOperation(pos, new_tax, new_tax.gross - pos.price))
-                self._invoice_dirty = True
+                if pos.price:
+                    # We do not consider the invoice dirty if only 0€-valued taxes are changed
+                    self._invoice_dirty = True
 
     def cancel_fee(self, fee: OrderFee):
         self._totaldiff_guesstimate -= fee.value