Use proper floor division operator

py3 changes the / operator from current integer division (floor
division) to instead be true division (float division). The // operator
exists in both py3 and py2 and always performs floor division.

Most of our important calculations already use Decimal with explicit
number of decimal points which is safe against this. But for some cases
like calculating pixels in pdfs and reports make sure that we explicitly
use the // so we don't risk a change in behaviour when we eventually
switch to py3.

1 files changed, 3 insertions, 1 deletions

diff --git a/postgresqleu/confreg/util.py b/postgresqleu/confreg/util.py
index 656da520..d3a79daa 100644
--- a/postgresqleu/confreg/util.py
+++ b/postgresqleu/confreg/util.py
@@ -3,6 +3,7 @@ from django.shortcuts import get_object_or_404
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
 
+from decimal import Decimal
 from datetime import datetime, date, timedelta
 import urllib
 from io import BytesIO
@@ -88,9 +89,10 @@ def invoicerows_for_registration(reg, update_used_vouchers):
                     else:
                         # Percentage discount. Can be either off the total or just the reg
                         if d.regonly:
+                            # regtype.cost is Decimal
                             discount = reg.regtype.cost * d.discountpercentage / 100
                         else:
-                            discount = current_total * d.discountpercentage / 100
+                            discount = Decimal(current_total) * d.discountpercentage / 100
                     if discount > 0:
                         r.append(['   Discount code %s' % d.code, 1, -discount, reg.conference.vat_registrations])
             except DiscountCode.DoesNotExist: