class ItemBase(models.Model):
    post = models.ForeignKey(Post, related_name='%(class)s_related')
    title = models.CharField(max_length=250)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

    def __str__(self):
        return self.title

    def render(self):
        return render_to_string('content/items/{}.html'.format(self._meta.model_name), {'item': self})


class Image(ItemBase):
    image_url = models.URLField(blank=True, null=True)
    image = models.ImageField(upload_to='posts/%Y/%m/%d', blank=True, null=True)

    def get_remote_image(self):
        if self.image_url and not self.image_file:
            result = urllib.urlretrieve(self.image_url)
            self.image_file.save(
                    self.title,
                    File(open(result[0]))
                    )
            self.save()