Method to_python

django/db/models/fields/__init__.py:1956–1973

(self, value)

        return "DurationField"

    def to_python(self, value):
        if value is None:
            return value
        if isinstance(value, datetime.timedelta):
            return value
        try:
            parsed = parse_duration(value)
        except ValueError:
            pass
        else:
            if parsed is not None:
                return parsed

        raise exceptions.ValidationError(
            self.error_messages["invalid"],
            code="invalid",
            params={"value": value},
        )

    def get_db_prep_value(self, value, connection, prepared=False):
        return connection.ops.adapt_durationfield_value(value)