forms.py

# -*- coding: utf-8 -*-

import re

from kay.i18n import lazy_gettext
from kay.utils.forms import RegexField


link_re = re.compile(
    'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+')

class LinkField(RegexField):
    messages = {
        'invalid': lazy_gettext(u'Enter a valid URL.'),
    }

    def __init__(self, *args, **kwargs):
        RegexField.__init__(self, link_re, *args, **kwargs)