boards/templatetags/board.py

from django.core.urlresolvers import reverse
from django.shortcuts import get_object_or_404
from boards.models import Post
from boards.views import thread
from django import template

register = template.Library()


@register.simple_tag(name='post_url')
def post_url(*args, **kwargs):
    post_id = args[0]

    post = get_object_or_404(Post, id=post_id)

    if post.thread:
        link = reverse(thread, kwargs={'post_id': post.thread.id}) \
            + '#' + str(post_id)
    else:
        link = reverse(thread, kwargs={'post_id': post_id})

    return link