Ensured that URL and id field are kept when using sparse fields (#1231)

Ensured that URL and id field are not filtered out when using sparse fields

URL field is considered a field in DRF but is not in JSON:API spec
therefore we may not exclude it.

ID on the other hand is a required field and may not be filtered.

Author: sliverc

CHANGELOG.md

@@ -14,6 +14,10 @@ any parts of the framework not mentioned in the documentation should generally b
 
 * Added `429 Too Many Requests` as a possible error response in the OpenAPI schema.
 
+### Fixed
+
+* Ensured that URL and id field are kept when using sparse fields (regression since 7.0.0)
+
 ## [7.0.0] - 2024-05-02
 
 ### Added

rest_framework_json_api/renderers.py

@@ -446,7 +446,10 @@ def _filter_sparse_fields(cls, serializer, fields, resource_name):
                 return {
                     field_name: field
                     for field_name, field, in fields.items()
-                    if field_name in sparse_fields
+                    if field.field_name in sparse_fields
+                    # URL field is not considered a field in JSON:API spec
+                    # but a link so need to keep it
+                    or field.field_name == api_settings.URL_FIELD_NAME
                 }
 
         return fields

rest_framework_json_api/serializers.py

@@ -94,10 +94,15 @@ def _readable_fields(self):
                         field
                         for field in readable_fields
                         if field.field_name in sparse_fields
+                        # URL field is not considered a field in JSON:API spec
+                        # but a link so need to keep it
                         or field.field_name == api_settings.URL_FIELD_NAME
+                        # ID is a required field which might have been overwritten
+                        # so need to keep it
+                        or field.field_name == "id"
                     )
             except AttributeError:
-                # no type on serializer, must be used only as only nested
+                # no type on serializer, may only be used nested
                 pass
 
         return readable_fields

tests/serializers.py

@@ -1,3 +1,5 @@
+from rest_framework.settings import api_settings
+
 from rest_framework_json_api import serializers
 from tests.models import (
     BasicModel,
@@ -32,6 +34,16 @@ class Meta:
         )
 
 
+class ForeignKeySourcetHyperlinkedSerializer(serializers.HyperlinkedModelSerializer):
+    class Meta:
+        model = ForeignKeySource
+        fields = (
+            "name",
+            "target",
+            api_settings.URL_FIELD_NAME,
+        )
+
+
 class ManyToManyTargetSerializer(serializers.ModelSerializer):
     class Meta:
         fields = ("name",)

tests/test_views.py

@@ -16,7 +16,9 @@
 from tests.serializers import BasicModelSerializer, ForeignKeyTargetSerializer
 from tests.views import (
     BasicModelViewSet,
+    ForeignKeySourcetHyperlinkedViewSet,
     ForeignKeySourceViewSet,
+    ForeignKeyTargetViewSet,
     ManyToManySourceViewSet,
     NestedRelatedSourceViewSet,
 )
@@ -87,7 +89,7 @@ def test_list(self, client, model):
 
     @pytest.mark.urls(__name__)
     def test_list_with_include_foreign_key(self, client, foreign_key_source):
-        url = reverse("foreign-key-source-list")
+        url = reverse("foreignkeysource-list")
         response = client.get(url, data={"include": "target"})
         assert response.status_code == status.HTTP_200_OK
         result = response.json()
@@ -156,7 +158,7 @@ def test_list_with_include_nested_related_field(
 
     @pytest.mark.urls(__name__)
     def test_list_with_invalid_include(self, client, foreign_key_source):
-        url = reverse("foreign-key-source-list")
+        url = reverse("foreignkeysource-list")
         response = client.get(url, data={"include": "invalid"})
         assert response.status_code == status.HTTP_400_BAD_REQUEST
         result = response.json()
@@ -195,7 +197,7 @@ def test_retrieve(self, client, model):
 
     @pytest.mark.urls(__name__)
     def test_retrieve_with_include_foreign_key(self, client, foreign_key_source):
-        url = reverse("foreign-key-source-detail", kwargs={"pk": foreign_key_source.pk})
+        url = reverse("foreignkeysource-detail", kwargs={"pk": foreign_key_source.pk})
         response = client.get(url, data={"include": "target"})
         assert response.status_code == status.HTTP_200_OK
         result = response.json()
@@ -208,6 +210,20 @@ def test_retrieve_with_include_foreign_key(self, client, foreign_key_source):
             }
         ] == result["included"]
 
+    @pytest.mark.urls(__name__)
+    def test_retrieve_hyperlinked_with_sparse_fields(self, client, foreign_key_source):
+        url = reverse(
+            "foreignkeysourcehyperlinked-detail", kwargs={"pk": foreign_key_source.pk}
+        )
+        response = client.get(url, data={"fields[ForeignKeySource]": "name"})
+        assert response.status_code == status.HTTP_200_OK
+        data = response.json()["data"]
+        assert data["attributes"] == {"name": foreign_key_source.name}
+        assert "relationships" not in data
+        assert data["links"] == {
+            "self": f"http://testserver/foreign_key_sources/{foreign_key_source.pk}/"
+        }
+
     @pytest.mark.urls(__name__)
     def test_patch(self, client, model):
         data = {
@@ -239,7 +255,7 @@ def test_delete(self, client, model):
 
     @pytest.mark.urls(__name__)
     def test_create_with_sparse_fields(self, client, foreign_key_target):
-        url = reverse("foreign-key-source-list")
+        url = reverse("foreignkeysource-list")
         data = {
             "data": {
                 "id": None,
@@ -379,6 +395,28 @@ def test_patch_with_custom_id(self, client):
             }
         }
 
+    @pytest.mark.urls(__name__)
+    def test_patch_with_custom_id_with_sparse_fields(self, client):
+        data = {
+            "data": {
+                "id": 2_193_102,
+                "type": "custom",
+                "attributes": {"body": "hello"},
+            }
+        }
+
+        url = reverse("custom-id")
+
+        response = client.patch(f"{url}?fields[custom]=body", data=data)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.json() == {
+            "data": {
+                "type": "custom",
+                "id": "2176ce",  # get_id() -> hex
+                "attributes": {"body": "hello"},
+            }
+        }
+
 
 # Routing setup
 
@@ -415,13 +453,16 @@ class CustomModelSerializer(serializers.Serializer):
     id = serializers.IntegerField()
 
 
-class CustomIdModelSerializer(serializers.Serializer):
+class CustomIdSerializer(serializers.Serializer):
     id = serializers.SerializerMethodField()
     body = serializers.CharField()
 
     def get_id(self, obj):
         return hex(obj.id)[2:]
 
+    class Meta:
+        resource_name = "custom"
+
 
 class CustomAPIView(APIView):
     parser_classes = [JSONParser]
@@ -443,14 +484,23 @@ class CustomIdAPIView(APIView):
     resource_name = "custom"
 
     def patch(self, request, *args, **kwargs):
-        serializer = CustomIdModelSerializer(CustomModel(request.data))
+        serializer = CustomIdSerializer(
+            CustomModel(request.data), context={"request": self.request}
+        )
         return Response(status=status.HTTP_200_OK, data=serializer.data)
 
 
+# TODO remove basename and use default (lowercase of model)
+# this makes using HyperlinkedIdentityField easier and reduces
+# configuration in general
 router = SimpleRouter()
 router.register(r"basic_models", BasicModelViewSet, basename="basic-model")
+router.register(r"foreign_key_sources", ForeignKeySourceViewSet)
+router.register(r"foreign_key_targets", ForeignKeyTargetViewSet)
 router.register(
-    r"foreign_key_sources", ForeignKeySourceViewSet, basename="foreign-key-source"
+    r"foreign_key_sources_hyperlinked",
+    ForeignKeySourcetHyperlinkedViewSet,
+    "foreignkeysourcehyperlinked",
 )
 router.register(
     r"many_to_many_sources", ManyToManySourceViewSet, basename="many-to-many-source"

tests/views.py

@@ -2,12 +2,15 @@
 from tests.models import (
     BasicModel,
     ForeignKeySource,
+    ForeignKeyTarget,
     ManyToManySource,
     NestedRelatedSource,
 )
 from tests.serializers import (
     BasicModelSerializer,
     ForeignKeySourceSerializer,
+    ForeignKeySourcetHyperlinkedSerializer,
+    ForeignKeyTargetSerializer,
     ManyToManySourceSerializer,
     NestedRelatedSourceSerializer,
 )
@@ -25,6 +28,18 @@ class ForeignKeySourceViewSet(ModelViewSet):
     ordering = ["name"]
 
 
+class ForeignKeySourcetHyperlinkedViewSet(ModelViewSet):
+    serializer_class = ForeignKeySourcetHyperlinkedSerializer
+    queryset = ForeignKeySource.objects.all()
+    ordering = ["name"]
+
+
+class ForeignKeyTargetViewSet(ModelViewSet):
+    serializer_class = ForeignKeyTargetSerializer
+    queryset = ForeignKeyTarget.objects.all()
+    ordering = ["name"]
+
+
 class ManyToManySourceViewSet(ModelViewSet):
     serializer_class = ManyToManySourceSerializer
     queryset = ManyToManySource.objects.all()