class SiteData(models.Model):
    """
    The is only one of these, it's just a hub for data belonging to the entire
    site. For example news articles that aren't associated with a Society.
    """
    name = models.CharField(max_length=50)
    news_articles = models.ManyToManyField(NewsArticle,
                                           related_name='newsarticle_set',
                                           blank=True)

    def number_of_news_articles(self):
        return self.news_articles.objects.count()

    class Meta:
        verbose_name_plural = 'Site data'

    class Admin:
        list_display = ('name', 'number_of_news_articles')