refactoring field to inherit from RegexField

localflavor/kw/forms.py

@@ -4,24 +4,39 @@
 from __future__ import unicode_literals
 
 import re
+import textwrap
 from datetime import date
 
 from django.core.validators import EMPTY_VALUES
 from django.forms import ValidationError
-from django.forms.fields import Field, Select
+from django.forms.fields import RegexField, Select
 from django.utils.translation import gettext_lazy as _
 
 from .kw_governorates import GOVERNORATE_CHOICES
 
-id_re = re.compile(r'''^(?P<initial>\d{1})
+
+id_re = re.compile(r'''^(?P<initial>\d)
                        (?P<yy>\d\d)
                        (?P<mm>\d\d)
                        (?P<dd>\d\d)
                        (?P<mid>\d{4})
-                       (?P<checksum>\d{1})''', re.VERBOSE)
+                       (?P<checksum>\d)''', re.VERBOSE)
+
+
+def is_valid_kw_civilid_checksum(value):
+    weight = (2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2)
+    calculated_checksum = 0
+    for i in range(11):
+        calculated_checksum += int(value[i]) * weight[i]
 
+    remainder = calculated_checksum % 11
+    checkdigit = 11 - remainder
+    if checkdigit != int(value[11]):
+        return False
+    return True
 
-class KWCivilIDNumberField(Field):
+
+class KWCivilIDNumberField(RegexField):
     """
     Kuwaiti Civil ID numbers are 12 digits, second to seventh digits
     represents the person's birthdate.
@@ -35,43 +50,32 @@ class KWCivilIDNumberField(Field):
         'invalid': _('Enter a valid Kuwaiti Civil ID number'),
     }
 
-    def has_valid_checksum(self, value):
-        weight = (2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2)
-        calculated_checksum = 0
-        for i in range(11):
-            calculated_checksum += int(value[i]) * weight[i]
-
-        remainder = calculated_checksum % 11
-        checkdigit = 11 - remainder
-        if checkdigit != int(value[11]):
-            return False
-        return True
+    def __init__(self, max_length=12, min_length=12, *args, **kwargs):
+        super(KWCivilIDNumberField, self).__init__(r'\d{12}',
+                                                   max_length,
+                                                   min_length, *args, **kwargs)
 
     def clean(self, value):
         super(KWCivilIDNumberField, self).clean(value)
         if value in EMPTY_VALUES:
             return ''
 
-        match = re.match(id_re, value)
-
-        if not match:
-            raise ValidationError(self.error_messages['invalid'])
-
-        gd = match.groupdict()
+        cc = value[0]  # Century value
+        yy, mm, dd = textwrap.wrap(value[1:7], 2)  # Date parts
 
         # Fix the dates so that those born
         # in 2000+ pass the validation check
-        if int(value[0]) == 3:
-            gd['yy'] = '20{}'.format(gd['yy'])
-        elif int(value[0]) == 2:
-            gd['yy'] = '19{}'.format(gd['yy'])
+        if int(cc) == 3:
+            yy = '20{}'.format(yy)
+        elif int(cc) == 2:
+            yy = '19{}'.format(yy)
 
         try:
-            date(int(gd['yy']), int(gd['mm']), int(gd['dd']))
+            date(int(yy), int(mm), int(dd))
         except ValueError:
             raise ValidationError(self.error_messages['invalid'])
 
-        if not self.has_valid_checksum(value):
+        if not is_valid_kw_civilid_checksum(value):
             raise ValidationError(self.error_messages['invalid'])
 
         return value
@@ -82,6 +86,7 @@ class KWGovernorateSelect(Select):
     A Select widget that uses a list of Kuwait governorates
     as its choices.
     """
+
     def __init__(self, attrs=None):
         super(KWGovernorateSelect, self).__init__(attrs,
                                                   choices=GOVERNORATE_CHOICES)