Create a separate migration for each field

netbox/circuits/migrations/0016_circuit_status_to_slug.py

@@ -0,0 +1,36 @@
+from django.db import migrations, models
+
+
+CIRCUIT_STATUS_CHOICES = (
+    (0, 'deprovisioning'),
+    (1, 'active'),
+    (2, 'planned'),
+    (3, 'provisioning'),
+    (4, 'offline'),
+    (5, 'decommissioned')
+)
+
+
+def circuit_status_to_slug(apps, schema_editor):
+    Circuit = apps.get_model('circuits', 'Circuit')
+    for id, slug in CIRCUIT_STATUS_CHOICES:
+        Circuit.objects.filter(status=str(id)).update(status=slug)
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ('circuits', '0015_custom_tag_models'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='circuit',
+            name='status',
+            field=models.CharField(default='active', max_length=50),
+        ),
+        migrations.RunPython(
+            code=circuit_status_to_slug
+        ),
+    ]