django rest framework us phone field

DRFUSPhoneField.py

import re

from django.core.validators import EMPTY_VALUES
from django.utils.encoding import smart_text

from rest_framework.fields import CharField
from localflavor.us.forms import USPhoneNumberField as FormUSPhoneNumberField, phone_digits_re
from django.core.exceptions import ValidationError


class USPhoneNumberField(CharField):
    """
    A form field that validates input as a U.S. phone number.
    """
    default_error_messages = {
        'invalid': _('Phone numbers must be in XXX-XXX-XXXX format.'),
    }
    type_name = 'USPhoneNumberField'
    type_label = 'phone'
    form_field_class = FormUSPhoneNumberField

    def validate(self, value):
        super(USPhoneNumberField, self).validate(value)
        if value in EMPTY_VALUES:
            return ''
        value = re.sub('(\(|\)|\s+)', '', smart_text(value))
        m = phone_digits_re.search(value)
        if m:
            return '%s-%s-%s' % (m.group(1), m.group(2), m.group(3))
        raise ValidationError(self.error_messages['invalid'])