Recaptcha with Django Comments

# Download devkit from recaptcha.org, and get a pub/private key
# and place captcha.py from the module in your application directory
# and add the RECAPTCHA_PUB_KEY and RECAPTCHA_PRIVATE_KEY vars
# to your settings

# Then add recaptcha_views.py to your root app directory with the following:

from django.contrib.comments.views.comments import post_free_comment
from django.http import Http404
import captcha
import settings

def free_comment_wrapper(request,extra_context={},context_processors=None):
    if request.POST:
        check_captcha = captcha.submit(request.POST.get('recaptcha_challenge_field',''), 
               request.POST.get('recaptcha_response_field',''), settings.RECAPTCHA_PRIVATE_KEY,   
               request.META['REMOTE_ADDR'])
        if check_captcha.is_valid is False:
            raise Http404, "Invalid Captcha Attempt"
        extra_context["recaptcha_html"]=captcha.displayhtml(settings.RECAPTCHA_PUB_KEY)
        return post_free_comment(request,extra_context,context_processors)
    raise Http404,"Only POSTs are allowed"

# This is a wrapper around post_free_comment, so preempt it in urls.py

    (r'^comments/postfree/$','recaptcha_views.free_comment_wrapper'),
    (r'^comments/',include('django.contrib.comments.urls.comments')),

# Now, to deal with the security, I needed a special template tag to generate the hash

from django.contrib.comments.models import Comment
from django.contrib.contenttypes.models import ContentType

def comment_security_hash(blogentry,opts):
    targ='%s:%s'%(ContentType.objects.get_for_model(blogentry).id,blogentry.id)
    return {"hash":Comment.objects.get_security_hash(opts,'','',targ)}

register.inclusion_tag("blog/templatetags/comment_security_hash.html")(comment_security_hash)

# I wanted this to work with a generic detail view, so here is mine
# (setup for the model "BlogEntry" in "blogs").

  (r'^blog/(?P<slug>[\w-]+)/$$', 'django.views.generic.list_detail.object_detail',{'queryset':BlogEntry.objects.public(),'slug_field':'slug',"extra_context":{"recaptcha_html":captcha.displayhtml(settings.RECAPTCHA_PUB_KEY),"contenttype_id":ContentType.objects.get(app_label__exact="blog",model__exact="blogentry").id}}),

# It is Really messy, but I use extra_context to get recaptcha_html 
# (the iframe) and then i pass  in the contettype_id to build the target input field.

# Finally, in the template code, we have to build a custom comment form.

         <form action="/comments/postfree/" method="post">
                <p><label for="id_person_name">Your name:</label> <input type="text" id="id_person_name" name="person_name" /></p>
                <p><label for="id_comment">Comment:</label><br /><textarea name="comment" id="id_comment" rows="10" cols="60"></textarea></p>
                <p>
                <input type="hidden" name="options" value="ip" />
                <input type="hidden" name="target" value="{{ contenttype_id }}:{{ object.id }}" />
                <input type="hidden" name="gonzo" value={% comment_security_hash object "ip" %} />
                {{ recaptcha_html }} 
                <input type="submit" name="post" value="Post Comment" />
                </p>
            </form>

# Now this is hardly an ideal setup, but allows me to use recaptcha with the 
# current trunk comments module. This gives me some time to work on 
# (or find out who is working on) captcha support in the actual trunk.