Django proxy model with additional model fields?

Question

I'm writing a Django app that works like a newspaper. I have articles and then I have customized versions of those articles that appear in certain contexts. So, I could have a version of an article that appears on the front page of the newspaper that has a shorter version of the article's original headline. So I have:

class Article(models.Model):
    """ A newspaper article with lots of fields """
    title = models.CharField(max_length=255)
    content = models.CharField(max_length=255)

    # Lots of fields...

I'd like to have a CustomArticlè object that is a proxy for the Articlè, but with an optional alternative headline:

class CustomArticle(Article):
    """ An alternate version of a article """
    alternate_title = models.CharField(max_length=255)

    @property
    def title(self):
        """ use the alternate title if there is one """
        if self.custom_title:
            return self.alternate_title
        else:
            return self.title
            
    class Meta:
        proxy = True
    
    # Other fields and methods

Unfortunately, I can't add new fields to a proxy:

>>> TypeError: Abstract base class containing model fields not permitted for proxy model 'CustomArticle'

So, I could do something like this:

class CustomArticle(models.Model):
    # Other methods...
    
    original = models.ForeignKey('Article')

    def __getattr__(self, name):
        if hasattr(self.original):
            return getattr(self.original, name)
        else:
            return super(self, CustomArticle).__getattr__(name)

But unfortunately, __getattr__ doesn't seem to work with Django models. The fields in the Article class could change, so it isn't practical to create a @property method for each one in CustomArticle. What is the right way to do this?

Answer 1

It looks like this might work for the __getattr__:

def __getattr__(self, key):

    if key not in ('original', '_ original_cache'):
        return getattr(self.original, key)      
    raise AttributeError("'%s' object has no attribute '%s'" % (self.__class__.__name__, key))