added support for partial updates in serializers (#731)

* added support for partial updates in serializers

* Add test to verify partial updates

Co-authored-by: Jonathan Kim <[email protected]>

Author: dan-klasson

graphene_django/rest_framework/mutation.py

@@ -102,8 +102,10 @@ def get_serializer_kwargs(cls, root, info, **input):
                 instance = get_object_or_404(
                     model_class, **{lookup_field: input[lookup_field]}
                 )
+                partial = True
             elif "create" in cls._meta.model_operations:
                 instance = None
+                partial = False
             else:
                 raise Exception(
                     'Invalid update operation. Input parameter "{}" required.'.format(
@@ -115,6 +117,7 @@ def get_serializer_kwargs(cls, root, info, **input):
                 "instance": instance,
                 "data": input,
                 "context": {"request": info.context},
+                "partial": partial,
             }
 
         return {"data": input, "context": {"request": info.context}}

graphene_django/rest_framework/tests/test_mutation.py

@@ -183,6 +183,16 @@ def test_model_update_mutate_and_get_payload_success():
     assert result.cool_name == "New Narf"
 
 
+@mark.django_db
+def test_model_partial_update_mutate_and_get_payload_success():
+    instance = MyFakeModel.objects.create(cool_name="Narf")
+    result = MyModelMutation.mutate_and_get_payload(
+        None, mock_info(), **{"id": instance.id}
+    )
+    assert result.errors is None
+    assert result.cool_name == "Narf"
+
+
 @mark.django_db
 def test_model_invalid_update_mutate_and_get_payload_success():
     class InvalidModelMutation(SerializerMutation):