fields.py 文件源码

def from_xml(self, elem, account):
        field_elem = elem.find(self.response_tag())
        val = None if field_elem is None else field_elem.text or None
        if val is not None:
            try:
                return self.value_cls(val)
            except (ValueError, InvalidOperation):
                log.warning("Cannot convert value '%s' on field '%s' to type %s", val, self.name, self.value_cls)
                return None
        return self.default