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