def _convert_bytes_to_str(self, column_name: str, value: Any) -> Union[str, Dict]:
        """
        Converts value to str from bytes for represent_as_base64_str columns.

        :param column_name: name of the field
        :type column_name: str
        :param value: value fo the field
        :type value: Any
        :return: converted value if needed, else original value
        :rtype: Any
        """
        if column_name not in self._bytes_fields:
            return value
        field = self.ormar_config.model_fields[column_name]
        if (
            value is not None
            and not isinstance(value, str)
            and field.represent_as_base64_str
        ):
            return base64.b64encode(value).decode()
        return value

        Converts value to str from bytes for represent_as_base64_str columns.

        :param column_name: name of the field
        :type column_name: str
        :param value: value fo the field
        :type value: Any
        :return: converted value if needed, else original value
        :rtype: Any
        
ormar/models/newbasemodel.py