Can't subclass the Message model, MessageManager breaks

[Dirk Groten]

When subclassing Message and using the MessageManager as the objects manager, queries like inbox don't work:

class Message(postman.models.Message):
    name = CharField(max_length=80, blank=True)

    class Meta
        manager_inheritance_from_future = True  # to use postman's MessageManager

Then in a shell:

> ./manage.py makemigrations
> ./manage.py migrate
> ./manage.py shell
>>> Message.objects.inbox(user=some_user)

psycopg2.ProgrammingError: column core_message.id does not exist
LINE 1: ...L) GROUP BY "postman_message"."thread_id") PM ON ("core_mess...

Note: here core_message is my subclass.

I think this is due to the as_sql custom query method in query.py.

I'm using Django 1.11.12 with Postman 3.6.1

[Dirk Groten]

I'm now circumventing the problem by returning postman.models.Message instances for the QuerySet with selected_related('message') to follow through to my message model:

class MessageManager(postman.models.MessageManager):
    def _folder(self, *args, **kwargs):
        return postman.models.Message.objects._folder(*args, **kwargs).selected_related('message')

class Message(postman.models.Message):
    objects = MessageManager()

A bit unfortunate, since now inbox, sent, etc... return instances of postman.models.Message and I have to do m.message.name to get to my added field. But works for now until we fix the issue.

[Dirk Groten]

I just made a pull request for this.

[Patrick Samson]

PR merged, and slightly refined.
Please confirm it works the same on your side.

[Dirk Groten]

It works, thanks for the quick merge.

[Dirk Groten]

Fixed.