I apply my condition to default managers indeed and I see no problem here. Default manager is just first manager defined on class(or on it's non concrete base). It has no additional magic.
About your example. I would never have suggested such a thing. And there will be no need to redeclare 'objects' manager in Comment class for you example after applying my patch. Please look at my example. For SimpleComment default manager is 'test_objects'. It doesn't have 'objects' attribute. For Comment before applying my patch there would be 'objects' attribute, but not in his own __dict__, but in Comment.__dict__, available through python mro. That's what I want to fix. In my example if you want to have 'objects' attribute available for SimpleComment now and for Comment after applying my patch you will have to redeclare it explicitly, because these classes have 'test_objects' as default manager. On Sunday, February 7, 2016 at 6:47:24 PM UTC+3, Shai Berger wrote: > > Reading your description again, it seems like you apply the condition to > default managers as well. Default managers are not "specific to the class > they > are defined on", and I see no problem in their inheritance. In particular: > > class BaseComment(models.Model): > ... some fields, no manager > > > class Comment(BaseComment): > ... some fields, still no manager > > Now, are you suggesting that Comment.objects must be defined explicitly? I > find > that odd. > > Shai. > > On Saturday 06 February 2016 18:07:22 Alex Poleha wrote: > > Thank you for the suggestion. Pull request is adjusted to give > deprecation > > warning instead of raising AttributeError. > > Yes, to silence the warning manager need to be be added to any subclass > > explicitly. It is explained in documentation > > < > https://docs.djangoproject.com/en/dev/topics/db/managers/#custom-managers- > > and-model-inheritance> for ages, so I don't think there would be a > problem. > > > > среда, 3 февраля 2016 г., 19:18:24 UTC+3 пользователь Tim Graham > написал: > > > Could this go through a deprecation where any use of the inherited > > > managers to be removed will raise a warning for a couple releases? If > > > anyone is relying on the behavior, they just need to add the managers > to > > > any subclasses, correct? > > > > > > On Wednesday, February 3, 2016 at 9:16:41 AM UTC-5, Alex Poleha wrote: > > >> Hi. > > >> > > >> According to documentation > > >> < > https://docs.djangoproject.com/en/1.9/topics/db/managers/#custom-manage > > >> rs-and-model-inheritance> managers defined on non-abstract base > classes > > >> are not inherited by child classes. In fact they're inherited via > > >> python MRO. I made pull request > > >> <https://github.com/django/django/pull/5797> to fix it. I find this > > >> > > >> inheritance embarrassing due to reasons, explained in documentation: > > >> 1. Managers defined on non-abstract base classes are *not* > inherited > > >> by child classes. If you want to reuse a manager from a > non-abstract > > >> base, redeclare it explicitly on the child class. These sorts of > > >> managers are likely to be fairly specific to the class they are > > >> defined on, so inheriting them can often lead to unexpected > results > > >> (particularly as far as the default manager goes). Therefore, they > > >> aren’t passed onto child classes. > > >> > > >> I also think this example shows some reasons why this inheritance is > > >> embarrasing: > > >> > > >> class SimpleComment(models.Model): > > >> test_objects = models.Manager() > > >> > > >> class BaseComment(models.Model): > > >> pass > > >> > > >> class Comment(BaseComment): > > >> test_objects = models.Manager() > > >> > > >> print(hasattr(models.SimpleComment, 'objects')) #False > > >> print(hasattr(models.Comment, 'objects')) #True, we may expect False > > >> here, since 'SimpleComment' gives False in similar sitation. > > >> print(models.Comment.objects.model) #<class 'BaseComment'>, this > manager > > >> is not contributed to 'Comment' class > > >> > > >> Tim Graham suggests asking if anyone relying on this inheritance and > > >> documentation should be fixed instead. Any suggestions? > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/792b29af-d2bb-4cfa-b93c-056d8c503e13%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
