Manager class example for working with generic keys. Keep content type lookups inside the manager.

managers.py

from django.db import models
from django.contrib.contenttypes.models import ContentType
 
 
class BookmarkManager(models.Manager):
 
    def _lookup_kwargs(self, **kwargs):
        owner = kwargs.pop('owner', None)
        if owner:
            owner_type = ContentType.objects.get_for_model(owner)
            owner_id = owner.id
            kwargs.update(owner_type=owner_type, owner_id=owner_id)
 
        item = kwargs.pop('item', None)
        if item:
            item_type = ContentType.objects.get_for_model(item)
            item_id = item.id
            kwargs.update(item_type=item_type, item_id=item_id)
 
        return kwargs
 
    def _create_kwargs(self, **kwargs):
        owner = kwargs.pop('owner', None)
        owner_id = kwargs.pop('owner_id', None)
        owner_type = kwargs.pop('owner_type', None)
        if owner:
            owner_type = ContentType.objects.get_for_model(owner)
            owner_id = owner.id
 
        item = kwargs.pop('item', None)
        item_id = kwargs.pop('item_id', None)
        item_type = kwargs.pop('item_type', None)
        if item:
            item_type = ContentType.objects.get_for_model(item)
            item_id = item.id
 
        kwargs.update(owner_type=owner_type, owner_id=owner_id,
                item_type=item_type, item_id=item_id)
        return kwargs
 
    def create(self, **kwargs):
        clean_kwargs = self._create_kwargs(**kwargs)
        return super(SavesManager, self).create(**clean_kwargs)
 
    def get_or_create(self, **kwargs):
        clean_kwargs = self._create_kwargs(**kwargs)
        return super(SavesManager, self).get_or_create(**clean_kwargs)
 
    def filter(self, **kwargs):
        clean_kwargs = self._lookup_kwargs(**kwargs)
        return super(SavesManager, self).filter(**clean_kwargs)
 
    def get(self, **kwargs):
        clean_kwargs = self._lookup_kwargs(**kwargs)
        return super(SavesManager, self).get(**clean_kwargs)