class IS_CPF_OR_CNPJ(object):

    def __init__(self, format=False, error_message=T('Número incorreto!')):
        self.error_message = error_message
        self.format = format

    def __call__(self, value):
        try:
            cl = str(''.join(c for c in value if c.isdigit()))

            if len(cl) == 11:
                cpf = cl
                cnpj = None
            elif len(cl) == 14:
                cpf = None
                cnpj = cl
            else:
                return value, self.error_message

            if cpf:
                def calcdv(numb):
                    result = int()
                    seq = reversed(
                        ((range(9, -1, -1)*2)[:len(numb)])
                    )
                    for digit, base in zip(numb, seq):
                        result += int(digit)*int(base)
                    dv = result % 11
                    return (dv-10) and dv or 0

                numb, xdv = cpf[:-2], cpf[-2:]

                dv1 = calcdv(numb)
                dv2 = calcdv(numb + str(dv1))
                if '%d%d' % (dv1, dv2) == xdv:
                    return self.doformat(cpf) if self.format else cpf, None
                else:
                    return cpf, T('CPF inválido')

            elif cnpj:

                intmap = map(int, cnpj)
                validate = intmap[:12]

                prod = [5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2]
                while len(validate) < 14:
                    r = sum([x*y for (x, y) in zip(validate, prod)]) % 11
                    f = 11 - r if r > 1 else 0
                    validate.append(f)
                    prod.insert(0, 6)

                if validate == intmap:
                    return self.doformat(cnpj) if self.format else cnpj, None

                else:
                    return cnpj, T('CNPJ inválido')

        except:
            return value, self.error_message

    def doformat(self, value):
            if len(value) == 11:
                result = value[0:3] + '.' + value[3:6] + '.' + value[6:9] + \
                    '-' + value[9:11]
            elif len(value) == 14:
                result = value[0:2] + '.' + value[2:5] + '.' + value[5:8] + \
                    '/' + value[8:12] + '-' + value[12:14]
            else:
                result = value
            return result

Simple validator.

Put the code in some model (db.py for example) and call it from requires when creating a table of form:

 Field('ident', 'string', length=20, requires=IS_CPF_OR_CNPJ())

Original: http://alexandremas.blogspot.com.br/