Define a default value for Order.payment_fee

src/pretix/base/migrations/0017_auto_20150308_1507.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0016_auto_20150308_1017'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='order',
+            name='payment_fee',
+            field=models.DecimalField(verbose_name='Payment method fee', default=0, max_digits=10, decimal_places=2),
+        ),
+    ]

src/pretix/base/models.py

@@ -1270,7 +1270,7 @@ class Order(Versionable):
     )
     payment_fee = models.DecimalField(
         decimal_places=2, max_digits=10,
-        verbose_name=_("Payment method fee")
+        default=0, verbose_name=_("Payment method fee")
     )
     payment_info = models.TextField(
         verbose_name=_("Payment information"),