Closes #8198: Custom field uniqueness (#16661)

* Closes #8198: Implement ability to enforce custom field uniqueness

* Add missing form fields & table columns for validation attributes

* Remove obsolete code

netbox/extras/api/customfields.py

@@ -6,6 +6,7 @@ from rest_framework.serializers import ValidationError
 
 from core.models import ObjectType
 from extras.choices import CustomFieldTypeChoices
+from extras.constants import CUSTOMFIELD_EMPTY_VALUES
 from extras.models import CustomField
 from utilities.api import get_serializer_for_model
 
@@ -75,7 +76,7 @@ class CustomFieldsDataField(Field):
 
         # Serialize object and multi-object values
         for cf in self._get_custom_fields():
-            if cf.name in data and data[cf.name] not in (None, []) and cf.type in (
+            if cf.name in data and data[cf.name] not in CUSTOMFIELD_EMPTY_VALUES and cf.type in (
                     CustomFieldTypeChoices.TYPE_OBJECT,
                     CustomFieldTypeChoices.TYPE_MULTIOBJECT
             ):

netbox/extras/api/serializers_/customfields.py

@@ -65,7 +65,7 @@ class CustomFieldSerializer(ValidatedModelSerializer):
             'id', 'url', 'display', 'object_types', 'type', 'related_object_type', 'data_type', 'name', 'label',
             'group_name', 'description', 'required', 'search_weight', 'filter_logic', 'ui_visible', 'ui_editable',
             'is_cloneable', 'default', 'weight', 'validation_minimum', 'validation_maximum', 'validation_regex',
-            'choice_set', 'comments', 'created', 'last_updated',
+            'validation_unique', 'choice_set', 'comments', 'created', 'last_updated',
         ]
         brief_fields = ('id', 'url', 'display', 'name', 'description')