Avoid AttributeError for PUT and PATCH methods when using APIView (#778)

Fixes silenced AttributeError in the case when lookup_url_kwarg doesn't exist in a view

Author: bpleshakov

CHANGELOG.md

@@ -8,6 +8,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 Note that in line with [Django REST Framework policy](http://www.django-rest-framework.org/topics/release-notes/),
 any parts of the framework not mentioned in the documentation should generally be considered private API, and may be subject to change.
 
+## [Unreleased]
+
+### Fixed
+
+* Avoid `AttributeError` for PUT and PATCH methods when using `APIView` 
+
 ## [3.1.0] - 2020-02-08
 
 ### Added

example/tests/test_parsers.py

@@ -1,10 +1,17 @@
 import json
 from io import BytesIO
 
+from django.conf.urls import url
 from django.test import TestCase, override_settings
+from django.urls import reverse
+from rest_framework import views, status
 from rest_framework.exceptions import ParseError
+from rest_framework.response import Response
+from rest_framework.test import APITestCase
 
+from rest_framework_json_api import serializers
 from rest_framework_json_api.parsers import JSONParser
+from rest_framework_json_api.renderers import JSONRenderer
 
 
 class TestJSONParser(TestCase):
@@ -69,3 +76,78 @@ def test_parse_invalid_data_key(self):
 
         with self.assertRaises(ParseError):
             parser.parse(stream, None, self.parser_context)
+
+
+class DummyDTO:
+    def __init__(self, response_dict):
+        for k, v in response_dict.items():
+            setattr(self, k, v)
+
+    @property
+    def pk(self):
+        return self.id if hasattr(self, 'id') else None
+
+
+class DummySerializer(serializers.Serializer):
+    body = serializers.CharField()
+    id = serializers.IntegerField()
+
+
+class DummyAPIView(views.APIView):
+    parser_classes = [JSONParser]
+    renderer_classes = [JSONRenderer]
+    resource_name = 'dummy'
+
+    def patch(self, request, *args, **kwargs):
+        serializer = DummySerializer(DummyDTO(request.data))
+        return Response(status=status.HTTP_200_OK, data=serializer.data)
+
+
+urlpatterns = [
+    url(r'repeater$', DummyAPIView.as_view(), name='repeater'),
+]
+
+
+class TestParserOnAPIView(APITestCase):
+
+    def setUp(self):
+        class MockRequest(object):
+            def __init__(self):
+                self.method = 'PATCH'
+
+        request = MockRequest()
+        # To be honest view string isn't resolved into actual view
+        self.parser_context = {'request': request, 'kwargs': {}, 'view': 'DummyAPIView'}
+
+        self.data = {
+            'data': {
+                'id': 123,
+                'type': 'strs',
+                'attributes': {
+                    'body': 'hello'
+                },
+            }
+        }
+
+        self.string = json.dumps(self.data)
+
+    def test_patch_doesnt_raise_attribute_error(self):
+        parser = JSONParser()
+
+        stream = BytesIO(self.string.encode('utf-8'))
+
+        data = parser.parse(stream, None, self.parser_context)
+
+        assert data['id'] == 123
+        assert data['body'] == 'hello'
+
+    @override_settings(ROOT_URLCONF=__name__)
+    def test_patch_request(self):
+        url = reverse('repeater')
+        data = self.data
+        data['data']['type'] = 'dummy'
+        response = self.client.patch(url, data=data)
+        data = response.json()
+
+        assert data['data']['id'] == str(123)
+        assert data['data']['attributes']['body'] == 'hello'

rest_framework_json_api/parsers.py

@@ -144,13 +144,14 @@ def parse(self, stream, media_type=None, parser_context=None):
             raise ParseError("The resource identifier object must contain an 'id' member")
 
         if request.method in ('PATCH', 'PUT'):
-            lookup_url_kwarg = view.lookup_url_kwarg or view.lookup_field
-            if str(data.get('id')) != str(view.kwargs[lookup_url_kwarg]):
+            lookup_url_kwarg = getattr(view, 'lookup_url_kwarg', None) or \
+                getattr(view, 'lookup_field', None)
+            if lookup_url_kwarg and str(data.get('id')) != str(view.kwargs[lookup_url_kwarg]):
                 raise exceptions.Conflict(
                     "The resource object's id ({data_id}) does not match url's "
                     "lookup id ({url_id})".format(
                         data_id=data.get('id'),
-                        url_id=view.kwargs[view.lookup_field]
+                        url_id=view.kwargs[lookup_url_kwarg]
                     )
                 )