Use serializer resource_name for nested objects in relationships too

Author: jsenecal

rest_framework_json_api/utils.py

@@ -376,7 +376,7 @@ def extract_relationships(fields, resource, resource_instance):
             if isinstance(serializer_data, list):
                 for position in range(len(serializer_data)):
                     nested_resource_instance = resource_instance_queryset[position]
-                    nested_resource_instance_type = get_resource_type_from_instance(nested_resource_instance)
+                    nested_resource_instance_type = get_resource_type_from_serializer(field.child)
                     relation_data.append(OrderedDict([
                         ('type', nested_resource_instance_type),
                         ('id', encoding.force_text(nested_resource_instance.pk))
@@ -386,9 +386,6 @@ def extract_relationships(fields, resource, resource_instance):
                 continue
 
         if isinstance(field, ModelSerializer):
-            relation_model = field.Meta.model
-            relation_type = format_relation_name(relation_model.__name__)
-
             data.update({
                 field_name: {
                     'data': (