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/models/customfields.py

@@ -180,6 +180,11 @@ class CustomField(CloningMixin, ExportTemplatesMixin, ChangeLoggedModel):
             'example, <code>^[A-Z]{3}$</code> will limit values to exactly three uppercase letters.'
         )
     )
+    validation_unique = models.BooleanField(
+        verbose_name=_('must be unique'),
+        default=False,
+        help_text=_('The value of this field must be unique for the assigned object')
+    )
     choice_set = models.ForeignKey(
         to='CustomFieldChoiceSet',
         on_delete=models.PROTECT,
@@ -217,7 +222,7 @@ class CustomField(CloningMixin, ExportTemplatesMixin, ChangeLoggedModel):
     clone_fields = (
         'object_types', 'type', 'related_object_type', 'group_name', 'description', 'required', 'search_weight',
         'filter_logic', 'default', 'weight', 'validation_minimum', 'validation_maximum', 'validation_regex',
-        'choice_set', 'ui_visible', 'ui_editable', 'is_cloneable',
+        'validation_unique', 'choice_set', 'ui_visible', 'ui_editable', 'is_cloneable',
     )
 
     class Meta:
@@ -334,6 +339,12 @@ class CustomField(CloningMixin, ExportTemplatesMixin, ChangeLoggedModel):
                 'validation_regex': _("Regular expression validation is supported only for text and URL fields")
             })
 
+        # Uniqueness can not be enforced for boolean fields
+        if self.validation_unique and self.type == CustomFieldTypeChoices.TYPE_BOOLEAN:
+            raise ValidationError({
+                'validation_unique': _("Uniqueness cannot be enforced for boolean fields")
+            })
+
         # Choice set must be set on selection fields, and *only* on selection fields
         if self.type in (
                 CustomFieldTypeChoices.TYPE_SELECT,