This is totally unwanted and doesn't match mongodb provider behaviour

sprox/sa/provider.py

@@ -591,23 +591,6 @@ def _modify_params_for_dates(self, entity, params):
  params[key] = dt
  return params
 
- def _remove_related_empty_params(self, obj, params, omit_fields=None):
- entity = obj.__class__
- mapper = class_mapper(entity)
- relations = self.get_relations(entity)
- for relation in relations:
- if omit_fields and relation in omit_fields:
- continue
-
- #clear out those items which are not found in the params list.
- if relation not in params or not params[relation]:
- related_items = getattr(obj, relation)
- if related_items is not None:
- if hasattr(related_items, '__iter__'):
- setattr(obj, relation, [])
- else:
- setattr(obj, relation, None)
-
  def _get_obj(self, entity, pkdict):
  entity = resolve_entity(entity)
  pk_names = self.get_primary_fields(entity)
@@ -636,7 +619,6 @@ def update(self, entity, params, omit_fields=None):
  pass
  setattr(obj, key, value)
 
- self._remove_related_empty_params(obj, params, omit_fields)
  self.session.flush()
  return obj