@property
def ordering_field(self):
    if (not hasattr(self, '_ordering_field')):
        self._ordering_field = self.get_ordering_field()
    return self._ordering_field
@property
def ordering_field(self):
    if (not hasattr(self, '_ordering_field')):
        self._ordering_field = self.get_ordering_field()
    return self._ordering_field