fixup! Do not lazy load forward relations

Author: Tim Csitkovics

rest_framework_json_api/serializers.py

@@ -184,9 +184,7 @@ def to_representation(self, instance):
             try:
                 context = getattr(self, '_context', {})
                 request = getattr(context.get('request', None), '_request', None)
-                get_dict = getattr(request, 'GET', None) if request is not None else {}
-                includes = get_dict['include'].split(',') if 'include' in get_dict else []
-                is_included = field.source in includes
+                is_included = field.source in get_included_resources(request)
                 if not is_included \
                         and isinstance(field, ModelSerializer) \
                         and hasattr(instance, field.source + "_id"):