Do not lazy load forward relations

If the forward relations are included, the renderer will break, so this optimization only works if it is not included.

Author: Tim Csitkovics

rest_framework_json_api/serializers.py

@@ -182,8 +182,10 @@ def to_representation(self, instance):
 
         for field in readable_fields:
             try:
-
-                if isinstance(field, ModelSerializer) and hasattr(field, field.source + "_id"):
+                context = getattr(self, '_context', {})
+                request = getattr(context.get('request', None), '_request', None)
+                is_included = request is not None and field.source in getattr(request, 'GET', None)
+                if not is_included and isinstance(field, ModelSerializer) and hasattr(instance, field.source + "_id"):
                     attribute = getattr(instance, field.source + "_id")
                     if attribute is None:
                         ret[field.field_name] = None