refactor: prefer pk/id from resource data over resource instance

test: add tests for `get_resource_id_from_instance` util function

Author: axieum

rest_framework_json_api/renderers.py

@@ -443,10 +443,12 @@ def build_json_resource_obj(
         # Determine type from the instance if the underlying model is polymorphic
         if force_type_resolution:
             resource_name = utils.get_resource_type_from_instance(resource_instance)
-        resource_id = utils.get_resource_id_from_instance(resource_instance)
+        resource_id = utils.get_resource_id_from_instance(
+            resource
+        ) or utils.get_resource_id_from_instance(resource_instance)
         resource_data = {
             "type": resource_name,
-            "id": resource_id,
+            "id": force_str(resource_id) if resource_id is not None else None,
             "attributes": cls.extract_attributes(fields, resource),
         }
         relationships = cls.extract_relationships(fields, resource, resource_instance)

rest_framework_json_api/utils.py

@@ -309,9 +309,9 @@ def get_resource_id_from_instance(instance):
     if not instance:
         return None
     elif hasattr(instance, "id"):
-        return encoding.force_str(instance.id)
+        return instance.id
     elif hasattr(instance, "pk"):
-        return encoding.force_str(instance.pk)
+        return instance.pk
     elif isinstance(instance, dict):
         return instance.get("id", instance.get("pk", None))
     return None

tests/test_utils.py

@@ -14,6 +14,7 @@
     format_resource_type,
     format_value,
     get_related_resource_type,
+    get_resource_id_from_instance,
     get_resource_name,
     get_resource_type_from_serializer,
     undo_format_field_name,
@@ -392,6 +393,35 @@ class SerializerWithoutResourceName(serializers.Serializer):
     )
 
 
+class ObjectWithId:
+    id: int = 9
+
+
+class ObjectWithPk:
+    pk: int = 7
+
+
+class ObjectWithPkAndId(ObjectWithId, ObjectWithPk):
+    pass
+
+
+@pytest.mark.parametrize(
+    "instance, expected",
+    [
+        (None, None),
+        (BasicModel(id=5), 5),
+        (ObjectWithId(), 9),
+        (ObjectWithPk(), 7),
+        (ObjectWithPkAndId(), 9),
+        ({"id": 11}, 11),
+        ({"pk": 13}, 13),
+        ({"pk": 11, "id": 13}, 13),
+    ],
+)
+def test_get_resource_id_from_instance(instance, expected):
+    assert get_resource_id_from_instance(instance) == expected
+
+
 @pytest.mark.parametrize(
     "message,pointer,response,result",
     [