90 lines
2.9 KiB
Python
90 lines
2.9 KiB
Python
# uid.py - functions for handling Swiss business identifiers
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# coding: utf-8
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#
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# Copyright (C) 2015 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""UID (Unternehmens-Identifikationsnummer, Swiss business identifier).
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The Swiss UID is used to uniquely identify businesses for taxation purposes.
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The number consists of a fixed "CHE" prefix, followed by 9 digits that are
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protected with a simple checksum.
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This module only supports the "new" format that was introduced in 2011 which
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completely replaced the "old" 6-digit format in 2014.
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More information is available at:
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https://www.uid.admin.ch/
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https://de.wikipedia.org/wiki/Unternehmens-Identifikationsnummer
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>>> validate('CHE-100.155.212')
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'CHE100155212'
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>>> validate('CHE-100.155.213')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> format('CHE100155212')
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'CHE-100.155.212'
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"""
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from stdnum.exceptions import *
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from stdnum.util import clean
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def compact(number):
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"""Convert the number to the minimal representation. This strips
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surrounding whitespace and separators."""
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return clean(number, ' -.').strip().upper()
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def calc_check_digit(number):
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"""Calculate the check digit for organisations. The number passed should
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not have the check digit included."""
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weights = (5, 4, 3, 2, 7, 6, 5, 4)
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s = sum(w * int(n) for w, n in zip(weights, number))
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return str((11 - s) % 11)
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def validate(number):
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"""Checks to see if the number provided is a valid number. This checks
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the length, formatting and check digit."""
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number = compact(number)
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if len(number) != 12:
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raise InvalidLength()
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if not number.startswith('CHE'):
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raise InvalidComponent()
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if not number[3:].isdigit():
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raise InvalidFormat()
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if number[-1] != calc_check_digit(number[3:-1]):
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raise InvalidChecksum()
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return number
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def is_valid(number):
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"""Checks to see if the number provided is a valid number. This checks
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the length, formatting and check digit."""
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try:
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return bool(validate(number))
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except ValidationError:
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return False
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def format(number):
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"""Reformat the passed number to the standard format."""
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number = compact(number)
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return number[:3] + '-' + '.'.join(
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number[i:i + 3] for i in range(3, len(number), 3))
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