Automatic geocoding in Django model

helpers.py

## Helper file to geocode address using Google Geocoder

import urllib, urllib2, simplejson
from django.utils.encoding import smart_str

def get_lat_lng(location):
    
    # Reference: http://djangosnippets.org/snippets/293/
    
    location = urllib.quote_plus(smart_str(location))
    url = 'http://maps.googleapis.com/maps/api/geocode/json?address=%s&sensor=false' % location
    response = urllib2.urlopen(url).read() 
    result = simplejson.loads(response)
    if result['status'] == 'OK':
       lat = str(result['results'][0]['geometry']['location']['lat'])
       lng = str(result['results'][0]['geometry']['location']['lng'])
       return '%s,%s' % (lat, lng)
    else:
        return ''

model.py

## Sample Model File

from django.db import models
from helpers import get_lat_lng ## Calling helper file

class Address(models.Model):
    address_1 = models.CharField(max_length=250)
    address_2 = models.CharField(max_length=250, null=True, blank=True)
    city = models.CharField(max_length=250)
    zipcode = models.CharField(max_length=20)
    state = models.CharField(max_length=250, null=True, blank=True)
    country = CountryField()
    latlng = models.CharField(blank=True, max_length=100)

    ## Geocode using full address
    def _get_full_address(self):
        return u'%s %s %s %s %s %s' % (self.address_1, self.address_2, self.city, self.state, self.country, self.zipcode)
    full_address = property(_get_full_address)

    ## Geocode by just using zipcode and country name (faster and more reliable)
    def _get_geo_address(self):
        return u'%s %s' % (self.country.name, self.zipcode)
    geo_address = property(_get_geo_address)


    def save(self, *args, **kwargs):
        if not self.latlng:
             if self.zipcode and self.country:
                 location = self.geo_address
                 self.latlng = get_lat_lng(location)
             else:
                 location = '+'.join(filter(None, (self.address_1, self.address_2, self.city, self.state, self.country)))
                 self.latlng = get_lat_lng(location)
        super(Address, self).save(*args, **kwargs)