Create a separate migration for each field

netbox/dcim/migrations/0079_rack_status_to_slug.py

@@ -0,0 +1,34 @@
+from django.db import migrations, models
+
+RACK_STATUS_CHOICES = (
+    (0, 'reserved'),
+    (1, 'available'),
+    (2, 'planned'),
+    (3, 'active'),
+    (4, 'deprecated'),
+)
+
+
+def rack_status_to_slug(apps, schema_editor):
+    Rack = apps.get_model('dcim', 'Rack')
+    for id, slug in RACK_STATUS_CHOICES:
+        Rack.objects.filter(status=str(id)).update(status=slug)
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ('dcim', '0078_rack_type_to_slug'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='rack',
+            name='status',
+            field=models.CharField(blank=True, default='active', max_length=50),
+        ),
+        migrations.RunPython(
+            code=rack_status_to_slug
+        ),
+    ]