Fixes #5176: Enforce content type restrictions when creating objects via the REST API

docs/release-notes/version-2.10.md

@@ -8,6 +8,7 @@
 
 ### Bug Fixes
 
+* [#5176](https://github.com/netbox-community/netbox/issues/5176) - Enforce content type restrictions when creating objects via the REST API
 * [#5358](https://github.com/netbox-community/netbox/issues/5358) - Fix user table configuration for VM interfaces
 * [#5374](https://github.com/netbox-community/netbox/issues/5374) - Fix exception thrown when tracing mid-point
 * [#5376](https://github.com/netbox-community/netbox/issues/5376) - Correct invalid custom field filter logic values

netbox/netbox/api/fields.py

@@ -94,14 +94,14 @@ class ContentTypeField(RelatedField):
     def to_internal_value(self, data):
         try:
             app_label, model = data.split('.')
-            return ContentType.objects.get_by_natural_key(app_label=app_label, model=model)
+            return self.queryset.get(app_label=app_label, model=model)
         except ObjectDoesNotExist:
             self.fail('does_not_exist', content_type=data)
-        except (TypeError, ValueError):
+        except (AttributeError, TypeError, ValueError):
             self.fail('invalid')
 
     def to_representation(self, obj):
-        return "{}.{}".format(obj.app_label, obj.model)
+        return f"{obj.app_label}.{obj.model}"
 
 
 class TimeZoneField(serializers.Field):

netbox/netbox/api/serializers.py

@@ -6,11 +6,10 @@ from rest_framework.exceptions import ValidationError
 from utilities.utils import dict_to_filter_params
 
 
-# TODO: We should probably take a fresh look at exactly what we're doing with this. There might be a more elegant
-# way to enforce model validation on the serializer.
 class ValidatedModelSerializer(serializers.ModelSerializer):
     """
-    Extends the built-in ModelSerializer to enforce calling clean() on the associated model during validation.
+    Extends the built-in ModelSerializer to enforce calling full_clean() on a copy of the associated instance during
+    validation. (DRF does not do this by default; see https://github.com/encode/django-rest-framework/issues/3144)
     """
     def validate(self, data):
 
@@ -31,8 +30,7 @@ class ValidatedModelSerializer(serializers.ModelSerializer):
             instance = self.instance
             for k, v in attrs.items():
                 setattr(instance, k, v)
-        instance.clean()
-        instance.validate_unique()
+        instance.full_clean()
 
         return data