From aca963d960f71f63c20da38ac22e6b78bc048e83 Mon Sep 17 00:00:00 2001
From: Raphael Michel <mail@raphaelmichel.de>
Date: Thu, 2 Jul 2020 19:24:18 +0200
Subject: [PATCH] Fix tax rate changes if there hasn't been a tax rate before

---
 src/pretix/base/services/orders.py | 4 ++--
 src/pretix/control/logdisplay.py   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/pretix/base/services/orders.py b/src/pretix/base/services/orders.py
index 3314eea55..017c3ce0a 100644
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -1605,14 +1605,14 @@ class OrderChangeManager:
                         'position': op.position.pk,
                         'positionid': op.position.positionid,
                         'addon_to': op.position.addon_to_id,
-                        'old_taxrule': op.position.tax_rule.pk,
+                        'old_taxrule': op.position.tax_rule.pk if op.position.tax_rate else None,
                         'new_taxrule': op.tax_rule.pk
                     })
                 elif isinstance(op.position, OrderFee):
                     self.order.log_action('pretix.event.order.changed.tax_rule', user=self.user, auth=self.auth, data={
                         'fee': op.position.pk,
                         'fee_type': op.position.fee_type,
-                        'old_taxrule': op.position.tax_rule.pk,
+                        'old_taxrule': op.position.tax_rule.pk if op.position.tax_rate else None,
                         'new_taxrule': op.tax_rule.pk
                     })
                 op.position._calculate_tax(op.tax_rule)
diff --git a/src/pretix/control/logdisplay.py b/src/pretix/control/logdisplay.py
index 4aec735c1..52638e43a 100644
--- a/src/pretix/control/logdisplay.py
+++ b/src/pretix/control/logdisplay.py
@@ -71,14 +71,14 @@ def _display_order_changed(event: Event, logentry: LogEntry):
             return text + ' ' + _('Tax rule of position #{posid} changed from {old_rule} '
                                   'to {new_rule}.').format(
                 posid=data.get('positionid', '?'),
-                old_rule=TaxRule.objects.get(pk=data['old_taxrule']),
+                old_rule=TaxRule.objects.get(pk=data['old_taxrule']) if data['old_taxrule'] else '–',
                 new_rule=TaxRule.objects.get(pk=data['new_taxrule']),
             )
         elif 'fee' in data:
             return text + ' ' + _('Tax rule of fee #{fee} changed from {old_rule} '
                                   'to {new_rule}.').format(
                 fee=data.get('fee', '?'),
-                old_rule=TaxRule.objects.get(pk=data['old_taxrule']),
+                old_rule=TaxRule.objects.get(pk=data['old_taxrule']) if data['old_taxrule'] else '–',
                 new_rule=TaxRule.objects.get(pk=data['new_taxrule']),
             )
     elif logentry.action_type == 'pretix.event.order.changed.addfee':