med/media/validators.py

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2019-08-11 07:22:22 +00:00
# -*- mode: python; coding: utf-8 -*-
# Copyright (C) 2017-2019 by BDE ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later
"""
Based on https://github.com/secnot/django-isbn-field
"""
from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _
from six import string_types
from stdnum import isbn
def isbn_validator(raw_isbn):
"""Check string is a valid ISBN number"""
isbn_to_check = raw_isbn.replace('-', '').replace(' ', '')
if not isinstance(isbn_to_check, string_types):
raise ValidationError(_(u'Invalid ISBN: Not a string'))
if len(isbn_to_check) != 10 and len(isbn_to_check) != 13:
raise ValidationError(_(u'Invalid ISBN: Wrong length'))
if not isbn.is_valid(isbn_to_check):
raise ValidationError(_(u'Invalid ISBN: Failed checksum'))
if isbn_to_check != isbn_to_check.upper():
raise ValidationError(_(u'Invalid ISBN: Only upper case allowed'))
return True