'This hook is called by the serializer instance,
prior to the validation call being made.'

def set_context(self, serializer):

    self.field_name = serializer.fields[self.field].source_attrs[(-1)]
    self.date_field_name = serializer.fields[self.date_field].source_attrs[(-1)]
    self.instance = getattr(serializer, u'instance', None)
