Accessing a proxy model from the parent within a template

I have the following Django model that extends the Post model from django basic blog:

from django.basic.blog.models import Post
from l10n.utils import lookup_translation

class ExtendedPost(Post):
    class Meta:
        proxy = True
    def translated_title(self, language_code=None):
        return lookup_translation(self, 'title', language_code)

I'm trying to use django basic blog's view by just overriding their template and making use of the new ExtendedPost behaviour in there:

{{ post.extendedpost.translated_title }}

But obviously this doesn't work because you can't just access a开发者_Python百科 subclass like that. How DO you do this type of thing?

---

Well, the view would still be referencing the original model, so you'd have to modify the view to pass in the ExtendedPost class.

You can't just define a proxy model and have it magically override the parent class.

1. Untested idea based on: Can django's auth_user.username be varchar(75)? How could that be done?

   from django.db.models.signals import class_prepared
   
   def add_func(sender, *args, **kwargs):
       if sender.__name__ == "Post" and sender.__module__ == "django-basic-blog-module":
           sender.translated_title = lambda self, language_code=None: lookup_translations(self, 'title', language_code)
   
   class_prepared.connect(add_func)
   

2. Override sys.modules

   import sys
   from django.basic.blog import models
   
   models.Post.translated_title = lambda self, language_code=None: lookup_translations(self, 'title', language_code)
   

---

You can make

{{ post.extendedpost.translated_title }}

work if you use multi-table inheritance rather than a proxy model.

However, introducing a whole new table just to add a function doesn't make a whole lot of sense.

---

This issue is too old but I found a solution that works for me and I will share it

you can just create a decorator like this:

def connect_proxy_to_model(property_name=None, return_copy=False):
    def get_proxy_func(proxy_class, self):
        if return_copy:
            proxy_obj = copy.deepcopy(self)
        else:
            proxy_obj = self
        proxy_obj.__class__ = proxy_class
        return proxy_obj

    def connect(proxy_class):
        name = property_name if property_name else proxy_class.__name__.lower()
        setattr(proxy_class.__base__, name, property(lambda self: get_proxy_func(proxy_class, self)))

    def wrapper(proxy_class):
        connect(proxy_class)
        return proxy_class

    return wrapper

And then you can decorate your proxy model with this:

from django.basic.blog.models import Post
from l10n.utils import lookup_translation


@connect_proxy_to_model(property_name='extendedpost', return_copy=True)
class ExtendedPost(Post):
    class Meta:
        proxy = True

    def translated_title(self, language_code=None):
        return lookup_translation(self, 'title', language_code)

Now you can use it just doing

{{ post.extendedpost.translated_title }}

The return_copy option that helps you if you want overwrite the current object ty