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CNPJ and CPF Validation for Models

Author:
tcarranza
Posted:
January 14, 2017
Language:
Python
Version:
Not specified
Score:
0 (after 0 ratings)

The code was placed inside a helper file without using a class. The Django validator was not designed to work with validator classes, it would appear, so retrieving the value from the field proved to be a hassle. Just create a helper file, import it on your model, and use the validator in the standard way, as such:

cnpj = models.CharField(unique=True, max_length=14, validators=[validate_CNPJ])
cpf = models.CharField(unique=True, max_length=14, validators=[validate_CPF])

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__author__ = "Théo Carranza [email protected]"
__copyright__ = "Copyright (C) 2017 Théo Carranza"
__license__ = "Public Domain"
__version__ = "1.0"

""" This is a slight modification from the class created by author dudus
 (https://djangosnippets.org/users/dudus/) for use on the model layer.
 It is optimized for Python 3.5  and PEP8 compliant. """

import re

from django.core.validators import EMPTY_VALUES
from django.forms import ValidationError
from django.utils.translation import ugettext_lazy as _

error_messages = {
    'invalid': _("Invalid CPF number."),
    'digits_only': _("This field requires only numbers."),
    'max_digits': _("This field requires exactly 11 digits."),
}


def DV_maker(v):
    if v >= 2:
        return 11 - v
    return 0


def validate_CPF(value):
    """
    Value can be either a string in the format XXX.XXX.XXX-XX or an
    11-digit number.
    """

    if value in EMPTY_VALUES:
        return u''
    if not value.isdigit():
        value = re.sub("[-\.]", "", value)
    orig_value = value[:]
    try:
        int(value)
    except ValueError:
        raise ValidationError(error_messages['digits_only'])
    if len(value) != 11:
        raise ValidationError(error_messages['max_digits'])
    orig_dv = value[-2:]

    new_1dv = sum([i * int(value[idx]) for idx, i in enumerate(range(10, 1, -1))])
    new_1dv = DV_maker(new_1dv % 11)
    value = value[:-2] + str(new_1dv) + value[-1]
    new_2dv = sum([i * int(value[idx]) for idx, i in enumerate(range(11, 1, -1))])
    new_2dv = DV_maker(new_2dv % 11)
    value = value[:-1] + str(new_2dv)
    if value[-2:] != orig_dv:
        raise ValidationError(error_messages['invalid'])

    return orig_value


def validate_CNPJ(value):
    """
    Value can be either a string in the format XX.XXX.XXX/XXXX-XX or a
    group of 14 characters.
    :type value: object
    """
    value = str(value)
    if value in EMPTY_VALUES:
        return u''
    if not value.isdigit():
        value = re.sub("[-/\.]", "", value)
    orig_value = value[:]
    try:
        int(value)
    except ValueError:
        raise ValidationError(error_messages['digits_only'])
    if len(value) > 14:
        raise ValidationError(error_messages['max_digits'])
    orig_dv = value[-2:]

    new_1dv = sum([i * int(value[idx]) for idx, i in enumerate(list(range(5, 1, -1)) + list(range(9, 1, -1)))])
    new_1dv = DV_maker(new_1dv % 11)
    value = value[:-2] + str(new_1dv) + value[-1]
    new_2dv = sum([i * int(value[idx]) for idx, i in enumerate(list(range(6, 1, -1)) + list(range(9, 1, -1)))])
    new_2dv = DV_maker(new_2dv % 11)
    value = value[:-1] + str(new_2dv)
    if value[-2:] != orig_dv:
        raise ValidationError(error_messages['invalid'])

    return orig_value

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