marshmallow notes

marshmallow.py

# creating a custom field that validates values on serialization/deserialization
class CustomField(object):
    # if inheriting from an built-in field like fields.Str
    def __init__(self, *args, **kwargs):
        super(CustomField, self).__init__(*args, **kwargs)

    def _validated(self, value):
        """Format the value or raise a :exc:`ValidationError` if an error occurs."""
        if value is None:
            return None
        # TODO: convert value to expected type and return
        raise ValidationError("{} is an invalid".format(value))

    def _serialize(self, value, attr, obj):
        validated = self._validated(value)
        return validated.display_name() if validated is not None else None

    def _deserialize(self, value, attr, data):
        return self._validated(value)