[Answered ]-What is the exact pattern of legal values for filling URLFields in Django?

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Looking through the source, it seems URLField is a CharField which adds a validators.URLValidator to the field’s validator list, and that’s imported from django.core.

From site-packages/django/core/validators.py:

class URLValidator(RegexValidator):
    regex = re.compile(
        r'^https?://' # http:// or https://
        r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?|' #domain...
        r'localhost|' #localhost...
        r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})' # ...or ip
        r'(?::\d+)?' # optional port
        r'(?:/?|[/?]\S+)$', re.IGNORECASE)

    def __init__(self, verify_exists=False, validator_user_agent=URL_VALIDATOR_USER_AGENT):
        super(URLValidator, self).__init__()
        self.verify_exists = verify_exists
        self.user_agent = validator_user_agent

    def __call__(self, value):
        try:
            super(URLValidator, self).__call__(value)
        except ValidationError, e:
            # Trivial case failed. Try for possible IDN domain
            if value:
                value = smart_unicode(value)
                scheme, netloc, path, query, fragment = urlparse.urlsplit(value)
                try:
                    netloc = netloc.encode('idna') # IDN -> ACE
                except UnicodeError: # invalid domain part
                    raise e
                url = urlparse.urlunsplit((scheme, netloc, path, query, fragment))
                super(URLValidator, self).__call__(url)
            else:
                raise
        else:
            url = value

        if self.verify_exists:
            import urllib2
            headers = {
                "Accept": "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5",
                "Accept-Language": "en-us,en;q=0.5",
                "Accept-Charset": "ISO-8859-1,utf-8;q=0.7,*;q=0.7",
                "Connection": "close",
                "User-Agent": self.user_agent,
            }
            try:
                req = urllib2.Request(url, None, headers)
                u = urllib2.urlopen(req)
            except ValueError:
                raise ValidationError(_(u'Enter a valid URL.'), code='invalid')
            except: # urllib2.URLError, httplib.InvalidURL, etc.
                raise ValidationError(_(u'This URL appears to be a broken link.'), code='invalid_link')

So it tries to validate to a regex, and if that fails it uses Python’s urlparse module to un-IDN the domain name and tries again.

👤Mike DeSimone

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