Use two managers in one model

[darbre]

Hi!

I have a Place model with subclasses Restaurant and Bar. I attached InheritanceManager from django-model-utils to Place to use the select_subclasses() method to get instances of the subclass.

from model_utils.managers import InheritanceManager


class Place(models.Model):
    # ...
    objects = InheritanceManager()

class Restaurant(Place):
    # ...

class Bar(Place):
    # ...

Everything worked fine. But now I want to set the order of the model Place.

...
objects = OrderedModelManager()
...

How to combine them?
Thanks.

[imomaliev]

You need to create new Manager class that inherits from both InheritanceManager and OrderedModelManager

class PlaceManager(InheritanceManager, OrderedModelManager)
    ...
    
class Place(models.Model):
    # ...
    objects = PlaceManager()

[darbre]

I have tried this method. If I try to move the object in the admin, I got an error:

AttributeError at /admin/myapp/place/6/move-top/
'InheritanceQuerySet' object has no attribute 'filter_by_order_with_respect_to'

[imomaliev]

You need to overload to queryset as well. And this queryset should be subclass of OrderedModelQueryset

[darbre]

objects = InheritanceManager.from_queryset(OrderedModelQuerySet)()

error: AttributeError
'OrderedModelQuerySet' object has no attribute 'select_subclasses'

[imomaliev]

You should've created new QuerySet that inherits OrderedModelQuerySet and InheritanceQuerySet and then passed it to your new PlaceManager