code: def to_primitive(self, value, context=None):
          
  
          data = []
  
          if not value.is_loaded:
              return None
  
          for model in value.models:
              if context and context.get('rel_ids'):
                  data.append(model.rid_value)
              else:
                  data.append({'rtype': model.rtype, 'rid': model.rid_value})
  
          return data
docs: Schematics serializer override
  
          The return values vary to indicate whether or not the
          relationships is loaded with values (list with members),
          loaded but no values (empty list), or never loaded &
          unknown if values exist or not.