Building my Django Weblog: Part 3

One day, while searching for something Django related, I ran into a really nicely done Django weblog. What caught my attention here, is that he came up with a way to spiffy up his comments display by showing a country flag for each commenter. It looks really spiffy. So I decided to play copycat.

Well, it only took a few minutes to implement it in the testing version of my own blog, and I showed it off to a couple of my friends in IRC. One of them, tjfontaine, said something along the lines of “oh neat, libgeoip.” Obviously, I hadn’t seen or heard of this libgeoip thing so I asked him about it and he linked me to it. Now this was interesting, because it comes with python bindings. And the best part, of course, is that it is in portage. So I installed it, and had a look at their usage sample. Essentially, you just download their ip to country map, which they update once a month, and so you don’t have to hit their servers everytime you do a lookup.

Next up, I wrote the templatetag to use GeoIP. In its entirety, it looks like this:

from django.template import Library
import GeoIP

register = Library()

def get_country(value, arg):
    ''' arg is the location of the flag imgs, eg '/media/img/flag/' '''
    try:
        gi = GeoIP.open('/usr/local/share/GeoIP/GeoIP.dat', GeoIP.GEOIP_STANDARD)
        code = gi.country_code_by_addr(value)
        name = gi.country_name_by_addr(value)
    except:
        return " "

    if code:
        img = "%s%s.png" % (arg, code.lower())
        return '<img src="%s" alt="%s" title="%s"/>' % (img, name, name)
    return " "

register.filter('get_country', get_country)

And to use it in a template, you would do something like this:

{% load iptocountry_filter %}
{{ comment.ip_address|get_country:"/media/images/site/flags/" }}

So by switching to this method, I no longer need to have a special Django model to store the ip to country maps (and since I use postgresql, I don’t have to go through the pain of altering any columns or updating my Django database every so often. Instead, I can just set up a monthly cron job to fetch maxmind’s database file and put it on my filesystem. And that is why you see those little flag icons on alll the comments on my site.

The only concern that some people might have is that GeoIP is a GPL-2 application, so there’s a concern that using it might virally make your own code GPL-2. If that is the case, then the above code is licensed under the terms of the GPL-2 as well, so use as you see fit within those terms, I guess. If it is not viral, then let’s say it’s a freebie. Either way, no warranty on it.

The idea is entirely Coulix’s and he deserves all the credit for it.