Closes #17761: Store empty CharField choices as null

netbox/circuits/migrations/0046_charfield_null_choices.py

@@ -0,0 +1,43 @@
+from django.db import migrations, models
+
+
+def set_null_values(apps, schema_editor):
+    """
+    Replace empty strings with null values.
+    """
+    Circuit = apps.get_model('circuits', 'Circuit')
+    CircuitGroupAssignment = apps.get_model('circuits', 'CircuitGroupAssignment')
+    CircuitTermination = apps.get_model('circuits', 'CircuitTermination')
+
+    Circuit.objects.filter(distance_unit='').update(distance_unit=None)
+    CircuitGroupAssignment.objects.filter(priority='').update(priority=None)
+    CircuitTermination.objects.filter(cable_end='').update(cable_end=None)
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('circuits', '0045_circuit_distance'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='circuit',
+            name='distance_unit',
+            field=models.CharField(blank=True, max_length=50, null=True),
+        ),
+        migrations.AlterField(
+            model_name='circuitgroupassignment',
+            name='priority',
+            field=models.CharField(blank=True, max_length=50, null=True),
+        ),
+        migrations.AlterField(
+            model_name='circuittermination',
+            name='cable_end',
+            field=models.CharField(blank=True, max_length=1, null=True),
+        ),
+        migrations.RunPython(
+            code=set_null_values,
+            reverse_code=migrations.RunPython.noop
+        ),
+    ]

netbox/circuits/models/circuits.py

@@ -187,7 +187,8 @@ class CircuitGroupAssignment(CustomFieldsMixin, ExportTemplatesMixin, TagsMixin,
         verbose_name=_('priority'),
         max_length=50,
         choices=CircuitPriorityChoices,
-        blank=True
+        blank=True,
+        null=True
     )
     prerequisite_models = (
         'circuits.Circuit',