From 5f2c513f9cfb7c4e20f3c970c602649e64de541d Mon Sep 17 00:00:00 2001
From: Malcolm Tredinnick <malcolm.tredinnick@gmail.com>
Date: Wed, 4 Apr 2007 11:40:08 +0000
Subject: [PATCH] Fixed #3919 -- Added German identity card number validation
 to German localflavor. Thanks, Jannis Leidel.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4922 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/contrib/localflavor/de/forms.py     | 64 ++++++++++++++++++++++
 tests/regressiontests/forms/localflavor.py | 13 +++++
 2 files changed, 77 insertions(+)

diff --git a/django/contrib/localflavor/de/forms.py b/django/contrib/localflavor/de/forms.py
index 7e1bee5b4e..c82d2d5b8d 100644
--- a/django/contrib/localflavor/de/forms.py
+++ b/django/contrib/localflavor/de/forms.py
@@ -7,6 +7,8 @@ from django.newforms.fields import Field, RegexField, Select, EMPTY_VALUES
 from django.utils.translation import gettext
 import re
 
+id_re = re.compile(r"^(?P<residence>\d{10})(?P<origin>\w{1,3})[-\ ]?(?P<birthday>\d{7})[-\ ]?(?P<validity>\d{7})[-\ ]?(?P<checksum>\d{1})$")
+
 class DEZipCodeField(RegexField):
     def __init__(self, *args, **kwargs):
         super(DEZipCodeField, self).__init__(r'^\d{5}$',
@@ -21,3 +23,65 @@ class DEStateSelect(Select):
     def __init__(self, attrs=None):
         from de_states import STATE_CHOICES # relative import
         super(DEStateSelect, self).__init__(attrs, choices=STATE_CHOICES)
+
+class DEIdentityCardNumberField(Field):
+    """
+    A German identity card number.
+
+    Checks the following rules to determine whether the number is valid:
+
+        * Conforms to the XXXXXXXXXXX-XXXXXXX-XXXXXXX-X format.
+        * No group consists entirely of zeroes.
+        * Included checksums match calculated checksums
+
+    Algorithm is documented at http://de.wikipedia.org/wiki/Personalausweis
+    """
+    def has_valid_checksum(self, number):
+        given_number, given_checksum = number[:-1], number[-1]
+        calculated_checksum = 0
+        fragment = ""
+        parameter = 7
+
+        for i in range(len(given_number)):
+          fragment = str(int(given_number[i])*parameter)
+          if fragment.isalnum():
+            calculated_checksum += int(fragment[-1])
+
+          if parameter == 1:
+            parameter = 7
+          elif parameter == 3:
+            parameter = 1
+          elif parameter ==7:
+            parameter = 3
+
+        if str(calculated_checksum)[-1] == given_checksum:
+            return True
+        return False
+
+    def clean(self, value):
+        super(DEIdentityCardNumberField, self).clean(value)
+        error_msg = gettext(u'Enter a valid German identity card number in XXXXXXXXXXX-XXXXXXX-XXXXXXX-X format')
+        if value in EMPTY_VALUES:
+            return u''
+        match = re.match(id_re, value)
+        if not match:
+            raise ValidationError(error_msg)
+
+        residence, origin, birthday, validity, checksum = \
+        match.groupdict()['residence'], match.groupdict()['origin'], \
+        match.groupdict()['birthday'], match.groupdict()['validity'], \
+        match.groupdict()['checksum']
+
+        if residence == '0000000000' or \
+           birthday == '0000000' or \
+           validity == '0000000':
+            raise ValidationError(error_msg)
+
+        all_digits = "%s%s%s%s" % (residence, birthday, validity, checksum)
+        if not self.has_valid_checksum(residence) or \
+            not self.has_valid_checksum(birthday) or \
+            not self.has_valid_checksum(validity) or \
+            not self.has_valid_checksum(all_digits):
+                raise ValidationError(error_msg)
+
+        return u'%s%s-%s-%s-%s' % (residence, origin, birthday, validity, checksum)
diff --git a/tests/regressiontests/forms/localflavor.py b/tests/regressiontests/forms/localflavor.py
index e30b52e366..419b597155 100644
--- a/tests/regressiontests/forms/localflavor.py
+++ b/tests/regressiontests/forms/localflavor.py
@@ -869,4 +869,17 @@ ValidationError: [u'Enter a zip code in the format XXXXX.']
 >>> w = DEStateSelect()
 >>> w.render('states', 'TH')
 u'<select name="states">\n<option value="BW">Baden-W\xfcrttemberg</option>\n<option value="BY">Bavaria</option>\n<option value="BE">Berlin</option>\n<option value="BB">Brandenburg</option>\n<option value="HB">Bremen</option>\n<option value="HH">Hamburg</option>\n<option value="HE">Hessen</option>\n<option value="MV">Mecklenburg-Western Pomerania</option>\n<option value="NI">Lower Saxony</option>\n<option value="NW">North Rhine-Westphalia</option>\n<option value="RP">Rhineland-Palatinate</option>\n<option value="SL">Saarland</option>\n<option value="SN">Saxony</option>\n<option value="ST">Saxony-Anhalt</option>\n<option value="SH">Schleswig-Holstein</option>\n<option value="TH" selected="selected">Thuringia</option>\n</select>'
+
+# DEIdentityCardNumberField #################################################
+
+>>> from django.contrib.localflavor.de.forms import DEIdentityCardNumberField
+>>> f = DEIdentityCardNumberField()
+>>> f.clean('7549313035D-6004103-0903042-0')
+u'7549313035D-6004103-0903042-0'
+>>> f.clean('9786324830D 6104243 0910271 2')
+u'9786324830D-6104243-0910271-2'
+>>> f.clean('0434657485D-6407276-0508137-9')
+Traceback (most recent call last):
+...
+ValidationError: [u'Enter a valid German identity card number in XXXXXXXXXXX-XXXXXXX-XXXXXXX-X format']
 """