the blog

"""
Comment validation for Django 1.0. By default, it runs one validator,
which derives its score from the number of links in a comment.

To add more validators, configure COMMENT_VALIDATORS in your Django settings,
adding the path to any callable you want to use for scoring comments. A
validator function should return a score between 0 and 1.

The scores from all validators are totalled to determine whether a comment is
spam. There are two thresholds determining the disposition of a comment: if 
the comment scores above COMMENT_SPAM_PUBLIC_THRESHOLD, its is_public 
attribute will be set to False. If it scores above 
COMMENT_SPAM_REJECT_THRESHOLD, the request will be rejected outright.

"""
import logging
import re

from django.conf import settings
from django.contrib.comments.models import Comment
from django.contrib.comments.signals import comment_will_be_posted

DEFAULT_COMMENT_VALIDATORS = (
    'fairview.comments.validate_link_limit',
)

LINK_RE = re.compile('https?://')
def validate_link_limit(comment):
    link_count = len(LINK_RE.findall(comment.comment))
    score = min(link_count, 10.0) / 10.0
    return score

def validate_comment(sender, comment, request, **kwargs):
    logger = logging.getLogger('fairview.comments.validate_comment')
    validators = []
    for path in getattr(settings, 'COMMENT_VALIDATORS', DEFAULT_COMMENT_VALIDATORS):
        i = path.rfind('.')
        module, attr = path[:i], path[i+1:]
        try:
            mod = __import__(module, {}, {}, [attr])
        except ImportError, e:
            raise ImproperlyConfigured('Error importing comment validation module %s: "%s"' % (module, e))
        try:
            func = getattr(mod, attr)
        except AttributeError:
            raise ImproperlyConfigured('Module "%s" does not define a "%s" callable comment validator' % (module, attr))
        validators.append(func)

    score = 0.0
    for validator in validators:
        score += validator(comment)
    if score > getattr(settings, 'COMMENT_SPAM_REJECT_THRESHOLD', 0.6):
        logger.info("""Comment spam score is %s; rejecting it.""" % score)
        logger.info("""Rejected comment info: IP Address: "%(ip_address)s" Name: "%(user_name)s" Email: "%(user_email)s" URL: "%(user_url)s" Comment: "%(comment)s" """ % comment.__dict__)
        return False
    if score > getattr(settings, 'COMMENT_SPAM_PUBLIC_THRESHOLD', 0.2):
        logger.info("""Comment spam score is %s; marking it non-public.""" % score)
        comment.is_public = False
    return True

comment_will_be_posted.connect(validate_comment, sender=Comment)