Convert data migration to Django migration

milestones/migrations/0001_initial.py

@@ -4,40 +4,6 @@ from __future__ import unicode_literals
 from django.db import models, migrations
 import django.utils.timezone
 import model_utils.fields
-from milestones.data import fetch_milestone_relationship_types
-
-# See this link for forwards_func and reverse_func
-# https://docs.djangoproject.com/en/1.8/ref/migration-operations/#runpython
-
-
-def forwards_func(apps, schema_editor):
-    """
-    Adds database entries for milestone relationship types defined in data.py
-    Performs existence checks before adding in order to avoid integrity errors
-    """
-    milestone_relationship_type_model = apps.get_model("milestones", "MilestoneRelationshipType")
-    db_alias = schema_editor.connection.alias
-
-    for name in fetch_milestone_relationship_types().values():
-        try:
-            milestone_relationship_type_model.objects.using(db_alias).get(name=name)
-        except milestone_relationship_type_model.DoesNotExist:
-            milestone_relationship_type_model.objects.using(db_alias).create(
-                name=name,
-                description='Autogenerated milestone relationship type "{}"'.format(name),
-            )
-
-
-def reverse_func(apps, schema_editor):
-    """
-    forwards_func() creates MilestoneRelationshipType instances,
-    so reverse_func() should delete them.
-    """
-    milestone_relationship_type_model = apps.get_model("milestones", "MilestoneRelationshipType")
-    db_alias = schema_editor.connection.alias
-
-    for name in fetch_milestone_relationship_types().values():
-        milestone_relationship_type_model.objects.using(db_alias).filter(name=name).delete()
 
 
 class Migration(migrations.Migration):
@@ -143,5 +109,4 @@ class Migration(migrations.Migration):
             name='coursecontentmilestone',
             unique_together=set([('course_id', 'content_id', 'milestone')]),
         ),
-        migrations.RunPython(forwards_func, reverse_func, False),
     ]

milestones/migrations/0002_data__seed_relationship_types.py

+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+from milestones.data import fetch_milestone_relationship_types
+
+
+def seed_relationship_types(apps, schema_editor):
+    """Seed the relationship types."""
+    MilestoneRelationshipType = apps.get_model("milestones", "MilestoneRelationshipType")
+    db_alias = schema_editor.connection.alias
+    for name in fetch_milestone_relationship_types().values():
+        MilestoneRelationshipType.objects.using(db_alias).get_or_create(
+            name=name,
+            description='Autogenerated milestone relationship type "{}"'.format(name),
+        )
+
+
+def delete_relationship_types(apps, schema_editor):
+    """Clean up any relationships we made."""
+    MilestoneRelationshipType = apps.get_model("milestones", "MilestoneRelationshipType")
+    db_alias = schema_editor.connection.alias
+    for name in fetch_milestone_relationship_types().values():
+        MilestoneRelationshipType.objects.using(db_alias).filter(name=name).delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('milestones', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.RunPython(seed_relationship_types, delete_relationship_types),
+    ]