Fixed referrals migration

Allow site column to be nullable, with no default. Related to #968.

ECOM-6230

ecommerce/referrals/migrations/0002_auto_20161011_1728.py

@@ -15,7 +15,7 @@ class Migration(migrations.Migration):
         migrations.AddField(
             model_name='referral',
             name='site',
-            field=models.ForeignKey(default=6, to='sites.Site'),
+            field=models.ForeignKey(to='sites.Site', null=True),
             preserve_default=False,
         ),
         migrations.AddField(

ecommerce/referrals/migrations/0003_auto_20161027_1738.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+"""
+This migration exists to fix the error introduced by https://github.com/edx/ecommerce/pull/968. The 0002 migration
+has been updated to setup the site column correctly for new installations. This migration ensures installations
+that previously ran 0002 have the column setup correctly.
+"""
+
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('referrals', '0002_auto_20161011_1728'),
+    ]
+
+    operations = [
+
+        migrations.AlterField(
+            model_name='referral',
+            name='site',
+            field=models.ForeignKey(to='sites.Site', null=True),
+        ),
+    ]

ecommerce/referrals/models.py

@@ -19,7 +19,7 @@ class Referral(TimeStampedModel):
         'utm_created_at',
     )
 
-    site = models.ForeignKey('sites.Site', null=False, blank=False)
+    site = models.ForeignKey('sites.Site', null=True, blank=False)
     basket = models.OneToOneField('basket.Basket', null=True, blank=True)
     order = models.OneToOneField('order.Order', null=True, blank=True)
     affiliate_id = models.CharField(_('Affiliate ID'), blank=True, default="", max_length=255)