I’ve been doing a bit of ecommerce work lately and one of my needs was a credit card field for a Django form. Ideally it needed to support all major cards (PayPal offers a good reference list) and be easily extendable in the future.
All I could find via Google was this older Django project and various blog posts, none of which really fit my needs.
After a bit more digging I decided to port over portions of Stripe’s jQuery.payment which does almost exactly what I needed.
| from django import forms | |
| from django.forms.widgets import TextInput | |
| from django.utils.translation import ugettext_lazy as _ | |
| class TelephoneInput(TextInput): | |
| # switch input type to type tel so that the numeric keyboard shows on mobile devices | |
| input_type = 'tel' | |
| class CreditCardField(forms.CharField): | |
| # validates almost all of the example cards from PayPal | |
| # https://www.paypalobjects.com/en_US/vhelp/paypalmanager_help/credit_card_numbers.htm | |
| cards = [ | |
| { | |
| 'type': 'maestro', | |
| 'patterns': [5018, 502, 503, 506, 56, 58, 639, 6220, 67], | |
| 'length': [12, 13, 14, 15, 16, 17, 18, 19], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'forbrugsforeningen', | |
| 'patterns': [600], | |
| 'length': [16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'dankort', | |
| 'patterns': [5019], | |
| 'length': [16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'visa', | |
| 'patterns': [4], | |
| 'length': [13, 16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'mastercard', | |
| 'patterns': [51, 52, 53, 54, 55, 22, 23, 24, 25, 26, 27], | |
| 'length': [16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'amex', | |
| 'patterns': [34, 37], | |
| 'length': [15], | |
| 'cvvLength': [3, 4], | |
| 'luhn': True | |
| }, { | |
| 'type': 'dinersclub', | |
| 'patterns': [30, 36, 38, 39], | |
| 'length': [14], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'discover', | |
| 'patterns': [60, 64, 65, 622], | |
| 'length': [16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| }, { | |
| 'type': 'unionpay', | |
| 'patterns': [62, 88], | |
| 'length': [16, 17, 18, 19], | |
| 'cvvLength': [3], | |
| 'luhn': False | |
| }, { | |
| 'type': 'jcb', | |
| 'patterns': [35], | |
| 'length': [16], | |
| 'cvvLength': [3], | |
| 'luhn': True | |
| } | |
| ] | |
| def __init__(self, placeholder=None, *args, **kwargs): | |
| super(CreditCardField, self).__init__( | |
| # override default widget | |
| widget=TelephoneInput(attrs={ | |
| 'placeholder': placeholder | |
| }) | |
| , *args, **kwargs) | |
| default_error_messages = { | |
| 'invalid': _(u'The credit card number is invalid'), | |
| } | |
| def clean(self, value): | |
| # ensure no spaces or dashes | |
| value = value.replace(' ', '').replace('-', '') | |
| # get the card type and its specs | |
| card = self.card_from_number(value) | |
| # if no card found, invalid | |
| if not card: | |
| raise forms.ValidationError(self.error_messages['invalid']) | |
| # check the length | |
| if not len(value) in card['length']: | |
| raise forms.ValidationError(self.error_messages['invalid']) | |
| # test luhn if necessary | |
| if card['luhn']: | |
| if not self.validate_mod10(value): | |
| raise forms.ValidationError(self.error_messages['invalid']) | |
| return value | |
| def card_from_number(self, num): | |
| # find this card, based on the card number, in the defined set of cards | |
| for card in self.cards: | |
| for pattern in card['patterns']: | |
| if (str(pattern) == str(num)[:len(str(pattern))]): | |
| return card | |
| def validate_mod10(self, num): | |
| # validate card number using the Luhn (mod 10) algorithm | |
| checksum, factor = 0, 1 | |
| for c in reversed(num): | |
| for c in str(factor * int(c)): | |
| checksum += int(c) | |
| factor = 3 – factor | |
| return checksum % 10 == 0 |
You can then use this field in your form:
| class CreditCardForm(ModelForm): | |
| card_number = CreditCardField(placeholder=u'0000 0000 0000 0000', min_length=12, max_length=19) |
